He could have been more sensitive but there is nothing homophobic about just being straight. He didn’t make any judgements about gay people, or any other disenfranchised group. His judgement/curiosity is towards straight males.
If you are bi curious and want to go to a glory hole and get excited about not knowing who is doing the service then guess what? You’re a beautiful person but you aren’t straight. So his question had nothing to do with you.
His question was for someone who has the same sexuality as him. It seems like he feels a specific way about something that comes from his sexuality and is wondering what the circumstances would be to make someone else that feels just like him about it to actually go through with it.