I would say go for it. It teaches them responsibility in a way. Lewis has 2 fish, not the same as a rabbit but hey ho lol and he knows he has to feed them every morning and a tiny few at night. The first thing he does when he wakes up is says I feed the fishes
me and Si clean out the tank because he's obviously too young. I know a few people with young children who have rabbits and they've never had any problems with them.
I think so long as you keep their hutch cleaned out regularly they don't really smell? Sounds like your getting a bargain with that hutch too.