He was liking underage pics

I have been seeing a guy for a month or 2 and everything was good. Recently I've seen on instagram he has been liking pictures of a girl who has barely turned 17 and commenting "🔥🔥" etc underneath her pictures. He is 23. I have a nearly 4 year old daughter and do not find this acceptable in the slightest. I cut contact with him completely 5 days ago. I'm not asking if im in the wrong for ending things but I feel like I should maybe message him and explain to him why I've ghosted on him and then maybe block him or should i just continue not to speak to him? He's messaged me maybe 2 times since asking why I'm not replying.