In defense of of the dialog with super friendly dude:
As a straight dude with a few non-straight friends, it seems that ANY time a straight guy has to point out his straightness to someone who is gay or bi always comes across harshly, whether he intends to be a dick or not. It's a simple way of saying "not interested," and anyone hoping there COULD be some interest is going to take that harsh - regardless of sexuality.
If super friendly dude came across to be interested in the MC, as it DID kinda seem, at first, almost any straight guy out there would have said SOMETHING to squash the idea of a hook up right away, so as to not lead super friendly dude on. Would it be harsh? Not in intent, but most likely in reception.