I don't think that's a dumb question at all. Ok, if you asked Bono "which is most important, U2, charity, or family," I am sure he would say family. But if you think about it, doesn't he spend more time on charity and U2, at least at the moment?
I know I'm going to be reviled for this, but I think he is currently putting his family third after those other two.
In a way, though, I think it would be more interesting to consider whether he would sooner give up U2 or his social work.