No, you can shoot the tube and it's implied Shepard survived. Not the same thing. Good headcanon on your part though.
Mac Walters is the one who compared ME3 to Breaking Bad, after all.
The intent of the scene is pretty much bone dead clear to everyone. The only one who wouldn't get the scene would be the ignoramus who doesn't want to get it. Otherwise, why would they put the scene in if they didn't intend for Shepard to live? So no, it's not headcanon. They could write it in pen, sharpie, smoke-signal, skywriting, or morse code, and you'd still refuse to believe it.
The problem is entirely with you. You don't want to get it.
As well, BW said the scene is open to interpretation. If you don't want Shepard to live, that's your problem. BW supports me when I say that he lived. Sorry.
And while SuperMac may have made a comparison to Breaking Bad, I fail to see how its relevant. I don't see anything in the game that ties into Breaking Bad at all. The ending? The game came out a year and a half before the BB series finale. So, I don't frankly think it makes sense to quote Walters here when you're providing no context as to the meaning. Which you can't do.
First is just your opinion. Bioware has made games where dragons, demigods, ghosts, demons, and other outright immortal beings are beatable. Why are the Reapers somehow special?
Second, I have already said that if beating the Reapers meant bringing down the entire freaking relay network instead of wiping out all AI, I'd do it in a heartbeat. Even knowing it would probably lead to a higher body count long term? Why? Because that's a sacrifice that makes sense. I'd find that an upbeat ending with a costly sacrifice.
So yeah, sucks for me, Shepard gets to be a genocidal monster instead.
Not just my opinion at all. Everybody basically says the Reapers are unbeatable by conventional means. Making an appeal to the history of BW games has no bearing on the Reapers or Mass Effect. It's a futuristic sci-fi setting with a basis in reality, not some fantasy world with magic and gods. That alone makes the essence of the Reapers incomparable to the other BW villains.
And a destroy beam that zaps technology and disrupts higher functions of machine intelligence makes sense. Yours is rather arbitrary, and it didn't happen regardless. And I'd say you have some screwed up morals and priorities if you find that better than sacrificing a willing ally to save everyone else and bring about a future devoid of the suffering that the Reapers or your scenario bring. Seriously, that's screwed up there, saying that you'd rather see that happen. So much for you holding the moral high-ground. You're more a killer than I'll ever be.
Well, you heard it here folks, blue space babes, magic rocks, and resurrection technology overseen by genetically engineered hotties in tight-fitting spandex is "a pretty realistic idea of space fantasy" 
As for the rest, how did you get through the first two games, with all it's sunshine and bunnies endings (by your estimate, at least)? I'd have expected you to walk away in disgust at the "pandering" 
Going by your arbitrary and changing definition of 'space-fantasy' it's hard to imagine any series that you wouldn't distort to fit your vision of genre. Same when you distort my words. Pretty realistic means that it isn't some simplistic, childish black and white world of good and evil where the righteous paragons always succeed in the end and the evil bad guys or pain and misery always fail. It's an ambiguous setting with no objective system or overarching theme of morality. It's like the real world. As grey as it gets, no matter how much of a good guy rule-abiding hero you are.
Quite easily. As a practical person willing to get the job done no matter whatever I have to do, I was able to reconcile my philosophy with the advantages presented in those games. I was also able to do it with the third game. You weren't.
How's it feel actually having to walk away in disgust because you saw how far and how useful your rules and heroism truly are? Pretty disgusted I'd imagine right?