And that poster whose first thought was gay behaviour...are men you meet frequently "gay"?
It wasn't my first thought, it was the OP's! And IMO for good reason. As I explained, otherwise I think the wording of the refusal would be very odd. "I'm not that kind of guy"? I take that to mean, well, he's not that kind of guy.
And, no, I have known and do know a fair number of gay men who are openly out, but I don't think I meet any more than the fairly small percentage that probably everyone in my state is likely to encounter. You really have to go to gay bars to meet gay men frequently, and although it's probably still true that the gay venues in my area have the best dance music, I'm really just too old for that now.
However, I didn't know this at the time:
I have quite a few gay friends, so I can usually get a sense if a guy is gay or not...
So if your gaydar is pretty good, then it's probably just a very odd choice of words (and now I'm really curious and hope you'll ask one day, and post an update!). Still, if he's straight, that doesn't preclude the non-sexual crush, either, IMO. Either way, I think that's what you're seeing.