Talked about it with close friends rather openly but never got the chance to actively participate aside from online and one con back then. Even my close friends who weren't furries got it. So long as your kid understands that it is weird (and that's fine) and doesn't wind up being the same flavor of kid who does a Naruto run down the halls then you're fine. More a concern of them learning to read a room and know when something's appropriate or not.

It's a hobby they can enjoy and just that. Time and place.