You waited until you were 24 to come out but for some reason (probably a selfish one) you are pressuring him to come out at 18? Back off and let him grow up a little first.
The decision of when to come out is his, not yours.
Well said Sixthson- I don't think I could have said it any better. <3.
"I always found him physically attractive, but not emotionally"
It really seems like you started seeing him for all of the wrong reasons =\, and it really makes me wonder if he's more than a boytoy.
Although, If you really do like him, than you should value his input and decision- Voice your opinion (story) and don't force it on him. Also you should really tell him that you'll be there to support him when he feels comfortable enough to come out may it be a month, a year, 5 years whenever- that is if you really do love him.
If you really care about someone, sometimes you need to learn how to put them first. If you are seeing him because you want something long-term, than there should be no feeling of shame and no rush for him to come out. If you were just using him, than maybe you should have that feeling of shame (discomfort, unease) when you talk to your friend or his family. If your intentions are well thought out- to bring out the best in him, to support him him, to love him, to be with him, to put him before yourself and never do him wrong than I don't see why you should feel uncomfortable or bothered by any of it.
The coming out stage is a process of accepting who you really are and not feeling ashamed for it. All he needs to know that he'll have people to listen and support him whenever he decides to. You forcing him to come out is only going to cause resentment towards you if things go south. If his parents are understanding and do see that you care about him, then I don't think there will be an issue down the line. All it means is that he wasn't at that point of his life he wasn't able to show them that part of his life, he wasn't comfortable with them knowing. It doesn't mean that he didn't value them, it means that he has respect for them, and ideally values what he might think are there values.
"At first he was just a hot piece of ass to me...but I'm starting to fall for him, and I've known for a while he's been head over heels for me."
Have you fallen for him, or are you just starting to? It really seems like you are quite indecisive if you actually like him or not. Which is why I said he might just be a boy toy, and you are caught up in the lust stage of things. Thinking oh this can be nice, maybe. Not exactly, what I want but it feels nice. I think you need to make up your mind. :X
"I've known for a while he's been head over heels for me"
Are you his first dating experience? I'm thinking so.
I would let him come to terms with his sexuality on his own pace. I mean what restrictions do you feel like it has placed on the relationship? Can you deal with them, or are they the dealbreaker?