I am certainly not an advocate of cheating, but a permanent ban is pretty severe. He cheated and should be punished. Many coaches (and people in general) cheat in some form or another. If all coaches who have ever cheated or tried to gain an unfair advantage were banned for life, a lot of coaches would be in other professions.
If someone speeds in their car, should they be banned from driving for life? How bout DUI....banned for life?
When folks get on a soap box like this and everyone starts piling on, it always strikes me how much greater everyone else's sins are than our own.
As for what he's teaching his kids, no one is good for nothing. Anyone can serve as a bad example. There is a lesson to be learned there.
My .02 worth.