Monosexuality is so weird.
But seriously, I just can't understand the mindset of someone who wouldn't even kiss someone of a gender they aren't attracted to if a person they really liked wanted them to. Seriously-we're not talking about having sex here, just kissing. Why is that even an issue? I guess because of homophobic masculinity complexes, which are all too common even among men who fully support political equality for gay people.
I disagree, I think it ultimately comes down to how much significance you put in swapping saliva - you evidently put a significant difference between that and sex, and yet I can't forsee a scenario where I'd willingly doing the former and yet being unwilling to do the latter. It fundamentally comes down to attraction for both. I don't think it's through masculine-driven homophobia either, because I'd be willing to bet many females would be similarly uncomfortable with (despite same patriarchal messages often encouraging it).