I suppose it matters where the defining line is, I guess. I've had doubts over my own sexuality before, which makes things morally trickier, but it usually seems to settle on the straight-but-kinky-enough-to-experiment-(once) level.
If being slightly grossed by two regular guys (or worse, muscular models) making out or gettin' it on counts, then ok... i'm mildy HP.
If it requires doing anything about it, from the level of telling them to cut it out - when you might not have done so with a straight couple (hey, it's not always the most comfortable thing to have ANY pair playing tonsil hockey in front of you) - then, no. I'm happy to live and let live. People can do things that make me squirm, but if it's not harming anyone or anything, well, leave them to it.
Got enough acquaintances of various kinds (friend, colleague, other... and probably family) who are gay, lesbian or bi (and i think - but have no way of proving, and wouldn't be crass enough to ask - trans in at least two cases, one in each direction) to not be able to afford to be an asshole about it anyway. They're just people. The way straight relationships work is a big enough pointer to the fact that you can't help who you love.
There's a line between prejudice and discrimination after all, and that is either carrying out, modifying or NOT carrying out a certain action because of your inbuilt bias. You can feel biased towards persons of a different race because of your upbringing, but if you're able to intellectualise that, realise why you feel that way, and be self disciplined enough to not act like a dick regardless of your reflexive feelings, you don't end up expressing it as racism. Not swinging the other way and ending up with an awkward expression of "white guilt" or the like is another, but related matter.
((All that said, i can't quite understand the very mincing gay types who seem to act like over-the-top drag queens but without the makeup or dress. Guess it's just one more personality type on the spectrum, but it does seem a bit wierd to pretty much turn yourself into a cartoon character that way. Still, blank mask of professionalism

))