The don't think kids are at much risk in PeeWee football. It isn't the violent high speed game it becomes as they get older.
Why do you even drive, man? Don't you know it kills you? Spoiler I'm kiddin', man... bringing that bit of news in here is somewhat of an unnecessary bit of information... you know?
Let him play, how much damage can one 5 year old really do to another? Unless it turns out the coach is some sort of pyscho and overworks them, I'd sign him up.