Here's my thinking on the "Cullen was going to be bi" thing. Yes, it's clear that at one point, the developers were considering Cullen was going to be bisexual. But, at some point prior to development, they changed their minds. When the game was released, Cullen was canonically straight. Gaider has confirmed it.
So, in other words, that ship has sailed. He's straight. I don't want them to change his orientation now (which we've seen people advocating for on BSN). Instead, I just want them to give us an m/m option like him (not exactly but similar) in a future game. I'm a little disappointed he's not bisexual, but I'm more than happy with Dorian and Bull, so it's all good in my book.
That being said, had they decided to pull the trigger on him being bisexual, I wouldn't see an issue with it. People can argue that he was 'clearly' straight in DA: O, but that's just not the case. It's was likely he was straight in DA: O. But there wouldn't need to be a giant retcon for a guy who showed interested in females at one point to actually be bisexual.