It is true that victims come out later. But in that case, it's their fault for waiting that long. I knew someone with an abusive husband that took forever for her to stand up to him the smallest amount to get a divorce, and he still harassed her. My family was VERY annoyed by her passiveness, even though we kept offering her help. On the one hand, yes, your a victim... but on the other hand, the longer you wait, the more you victimize yourself.
If what Kevin was doing was that bad, they should have said something right away. They didn't. They only acted because they knew they could get money. But then again, we're trusting the judgement of teenage boys who were on a chatroom. They gave their names and everything, something they've been telling kids since the 90's. Here's the thing. Imagine if it wasn't Kevin, but someone pretending to be them. They could have been killed. If Kevin did something, yes... shame on him. But they were dumb enough to go for it, so they aren't blameless.