Okay, I don’t normally offer personal advice, but since I’ve had extensive experience with kids, pets, and caring, I will go out on a limb here (especially considering that it’s Handy, who never asks for advice.)
What I would do, if I were in your shoes (serious answer):
I would STRONGLY express my desire to the kid that he resume ownership of his rabbits PDQ. I would say, gently but firmly, “These are your rabbits. I’ve cared for them for two years now, while you weren’t able to have pets, but now that you’re living in a place where you CAN have pets, it’s time for you to take them back.” Express to him the fact that you have paid your dues, that if you had wanted to have rabbits as pets, you would have gone out and procured some for yourself.
And I would say it as though I really meant it (which, actually, I would. I’ve paid some heavy dues myself, caring for kids’ pets when the novelty wears off). I would also point out that if he doesn’t resume ownership of his rabbits, they are going to see the inside of the local Humane Society within a certain time frame, and I would say that as though I meant it, too. Set a time limit and stick to it.
What I would do, if I were in your shoes (not-serious answer): Tell him to come get the damn rabbits–once. Then don’t mention it again. Then, a few weeks later, when of course he hasn’t come over to get the rabbits, invite him for supper, hide the rabbits, and serve fried chicken (find one of those skinny little whole fryers and cut it up). After supper, when he asks where the rabbits are, stare sorrowfully at the serving platter and say, “Gee, I’m sorry, I thought you didn’t want them anymore, and I was a little short on grocery money this month…” Then burp loudly.