This will cause a row but here goes. Such perverts (yes, I agree that is exactly what he is) along with other paedophiles, rapists, necrophile etc etc, are born with their problem. I don't believe for one minute that such people want, or choose, to be as they are, they are a victim of their birth. You may like to dream up all manner of punishments you think suitable but it won't change anything, in fact, it will just perpetuate the problem.
Unless, or until, we find a way of helping such people cope with their poblems this abominable behavour will continue ad infinitum.
Just in case you are wondering, I am eternally grateful that I was blessed with a very normal disposition.