Why would my ex sext a minor but also liked watching shows with catching predators?

My ex (23M) sexted a 15-year-old, but he was also was really into the show 'To Catch a Predator' and also watching a youtube channel of a guy who used to catch predators..

Psychologically, what could explain this contradiction? I am confused:

To clarify my exes behavior wasn’t a pattern. Idk if he falls into the term “predator”. He did it only once at 23 and they didn’t really meet but he did sext with a 15 year old for like 1-2 days, even after she told him her age…