If said straight guy is also grossed out by kissing of other pairings of humans, then definitely, yeah.
I also imagine that some people are not actually gay, but rather are just worried that it might invoke something in them, which would cause social problems for them. So, to block out any such impression, they develop this grossness reaction. I used to have that, too, when I was young / socially dependent on people inaccepting of homosexuality.
I do not see why else someone should be grossed out by two male lips touching.
Yeah, then you're a person that's grossed out by any kissing. That makes sense to me.
Calling them "male lips" was kind of tongue-in-cheek, similar to how a male nipple is perfectly a-ok, but a female nipple needs to be censored, even though they're visually generally indistinguishable.
Nobody can stop you from thinking about cock sir, if you love cock so much you just want to think about it all day, that's fine. No need to dress it up as "being grossed out"