Ross says they made it up and he was Never DPR. I'd believe it. But still. If, best case he had moved on and had nothing to do with the site but still just had access, he would have known what it had turned into.
If I started a website then later found out people were using it to arrange murders for hire, I would not just ignore it and hope it went away.
Best case, Ross knew and did nothing.
Worst case, Ross was DRP all along and this is just a defense strategy.