For the purposes of this response, assume instances of me saying "Shepard" or "Shep" are in reference to Bro Shep.
Kaidan, in ME2, tells Shepard that losing him was like losing a limb. All the camera shots of them talking in ME1 somehow managed to have more sexual tension than actual porn (the lighting, the slow walk, the turn, the staredown - seriously, those two could just have started ripping their shirts off and it would have seemed more natural than their talking). I don't know what game you've played, but Kaiden being into Shepard is not out of character.
I'll go beyond your post, just for the sake of definitively debunking all this.
• Kaidan is a submissive man in professional environments, he prefers to follow someone he trusts/respects rather than leading, which is established and reestablished multiple times throughout the series.
• Kaidan makes the limb comment because he enjoys being part of the Normandy very much, he also enjoys serving under Shepard very much and he has huge amount of respect for Shepard. So when Shep is killed, for him, given his personality (see above), it is like losing one of his limbs. A person could also argue they're very close "bros" so the death hit him really hard due to losing a close friend.
• All the camera shots lightning and "staredown" in ME are gender and romance unspecific, and therefore they don't indicate anything at all. Using these scenes for head canons, fan fiction, or personal stories is awesome, but they have nothing to do with Kaidan's independent canon. Finally, Kaidan was not bisexual in ME1 or ME2 so you claiming Shep independent canon bisexual content exists in those two chapters of the trilogy is ridiculous.
• In ME3 Kaidan's not having approached Bro Shep sooner makes no sense and is out of character given how he behaves the two other times he had strong romantic feelings for someone. One could assert that maybe his relationship with Bro Shep was unique, but this would be untrue, because his relationship with Bro Shep in ME1 and ME2 directly parallels FemShep throughout all emotional checkpoints (Lots of respect, enjoying serving under their command, personal admiration/friendship) except sexual attraction/romantic love. One could also assert that it had to do with some sort of hangup about homosexual intimacy, but this doesn't make sense because all evidence suggests that Mass Effect takes place in a post tolerance galaxy, and it be illogical to think Kaidan would have an atypical personal hangup like that when nothing else about his character suggests he's that sort of person. As such, we're forced to conclude that the "explanation" is bullshit, and ultimately existed for the exclusive purpose of trying explaining a playersexual OOC M/M relationship they forced on Kaidan in ME3 in order to appear progressive.
• The other "explanation" I've heard tossed around for the M/M romance in 3 was that Kaidan felt Bro Shep was "too busy with work" and didn't say anything. This is also OOC and not believable, because Kaidan is an emotional man and very much influenced by his heart, to the point he has difficulty controlling himself when he's around someone with whom he has strong romantic feelings. Note how Kaidan disregards Brain-Camp's implied rules on fraternization in order to get closer to Rahna and even flies into a biotic rage and kills Vyrnnus in order to protect her, and Rahna isn't even his girlfriend. With FemShep, who he's falling in love with very early in the Trilogy, there are multiple instances of him slipping up and complimenting her when he probably shouldn't, one of the biggest examples of this being the overlook scene on Citadel with Ash, Shep and himself, where he reacts with lots of excitement when Shepard talks about things to love about humanity and it's obvious he's crushing on her hard. He's also willing to walk the line of military regulations on fraternization in order to pursue Shep, and eventually willing to ignore them completely so he can just be with her. Therefore this idea that he, a nesting ride or die for love man, was crushing on Bro Shep but said nothing is simply absurd and completely unbelievable.
• Kaidan indicates interest in women numerous times(Getting mesmerized at Cora's Den by the Strippers, saying he cares about Femshep even outside a romance, Telling Broshep he saw Liara first if they pursue her, Talking about Benezia's sexy dress, talking about Asari being so sexy, commenting on EDI's sexbot body looking nice, ECT) but never in men, not a single comment, ever. Which is OOC and unbelievable in a post tolerance galaxy given his personality.
• The Bro Shep x Kaidan romance has zero content of it's own, and cut content from the story from which it came. This, when combined with all the evidence above strongly suggests it existences only as a playersexual M/M romance option because of them trying to shove "progressive" content into characters where it didn't belong, and to give a gay Bro Sheps a second LI option.
I could probably go further if I put my mind to it, but...
Characters don't turn gay or bi because of player fetishization, or because it suits somebody's head canon, and this whole situation should be used as a huge underscore of BW's massive failure at attempting to turn heterosexual characters bi in order to placate their LGB fanbase. What they should have been doing all along was writing new gay, bi and lesbian characters to join their already pre existing casts, who could be interesting and fresh representations of LGB and provide something for the fans to whom they were being created for to love and enjoy and have all to themselves, not degrading pre existing characters by giving them weird and ooc edits to their sexuality.
You can get your clique to run and up vote your post in some desperate attempt to validate it all you want, but that doesn't change the fact Kaidan isn't bisexual simply because you want him to be, or because BW tried and failed to assassinate his character with that modded tripe.
I assume you enjoy his M/M romance, and I'm happy for you. Just like I'm happy for everyone who enjoys Kaidan because I love everything about him and am always glad when other people enjoy him, and I'm just fine with compartmentalizing my misgivings about that romance for the sake of more people getting to enjoy Kaidan, but at the end of the day he's still ultimately a heterosexual character.
To you (or, if not, a lot of M/M romancers) he was just the most ideal piece of meat on the rack. But for me, Kaidan is my favorite BW character and his is my favorite romance story (arguably in anything) and I would hope that people might actually listen to myself and other ride or die Kaidan fans who debunked the fiction of his bisexuality multiple times instead being endlessly being contrary and trying to prove he's bisexual with a bunch of fairground arguments and random nonsense.
People should take this fracus as an example that for all the way they've come BW still has a long way to go with M/M representation, and should be that much more motivated in wanting a real M/M romance option like Kaidan, and not be satisfied until they get it.