Um, that was offensive, and you don't have to be gay to think it was. I'm not. He was right to apologize, and I'm glad that whoever wrote it didn't put in the "I'm sorry if anyone was offended" non-apology.
Why was it offensive? Because he said something that he thought was a double-entendre for gay sex, and had to immediately clarify that he wasn't gay, because it would be embarrassing to be gay. It's that very attitude that (*most of*) the gay community is trying to combat. No, you don't need to be embarrassed to be gay. And no, you don't need to laugh about every time a series of words sounds (to you) like something gay people do in the bedroom (especially since you probably have no idea what gay people do in the bedroom -- I know I don't.)
I don't think Hibbert was trying to be malicious at all - he was, quite simply, making a (lewd, I suppose, although I still don't understand what he thought the double-meaning was) joke. But it's the attitudes behind the joke that are offensive, and what people need to think about. (There are also definitely some people who find "homo" in itself to be a slur. I think they are correct (and if the moderators agree with me, I apologize for my use), but debating what is and isn't a slur misses the larger point, in my opinion). Hibbert didn't need to acknowledge the double-meaning at all, or if he couldn't resist, could have said something that meant "no double-meaning intended", instead of "I'm not gay."
*I acknowledge that they gay community is large and diverse, and may not all have the same priorities. You might even know someone who doesn't care about this. That doesn't mean that those who do are wrong, just as it doesn't mean that those who don't are wrong.*