I think that the toxicity also comes from the fact that he clearly thinks masturbation is a sin. Because if he just said "it's not wrong to have lots of sexual thoughts all the time, even if my wife isn't in the mood for sex - so I took matters into my own hands and became good at sexually satisfying MYSELF as well" - then that would have been a really healthy message. Because I get it, having a situation with mismatched libido in a relationship sucks. That's why masturbation is so important to a healthy sexual life.