Well, obviously that is the case. There's a reason why TV Tropes has entries for Straight Gay
and Camp Straight
, these things clearly exist as tropes in the media, so therefore they exist in reality too. It is yet another layer to the complicated spectrum that is human sexuality. (And remember this is without even mentioning asexuality, or separating out sexuality from romance).
As I said, you really can't tell a character's sexuality just by a limited view of their behaviour.
Also, the gay rights movement would get nowhere without our straight allies. So, thank you.
Actually, we don't know that. It is likely he's going to be more "bromantic" towards a possible male PC love interest. He has been taught to treat women one way, and men another - that wouldn't change if he was bisexual.