I don't think jump the gun to him becoming a sex offender. They're two entirely different entities.

As for his behaviour when he was younger? He was young and immature and probably thought he was having a bit of fun but has likely stopped as he said.

I'm probably a biased one to speak about porn. I watch it. I don't consider it cheating.

As for swapping nude pics? That's a no no and it needs to stop.