Youtube comments like these are so insensitive I don't think he would get in any actual trouble, but you could try reporting it and see what happens. Not this being on the Kill Em With Kindness video though
Don't these teenagers learn? I swear some Dutch girl was arrested for sending a death threat. I have no idea where this person is, he may be in North America, but I think a lot of the pop girl trolls seem to be outside of America so they think they can sit or do anything and not get in trouble.