“Most internet forums where pedophiles congregate to obtain peer support and feel less isolated — including the Virtuous Pedophiles forum — have strict rules forbidding members from admitting to any illegal activity.”
You are worried enough about it that you forbid they admit illegal activity in your groups. They should admit illegal activity, to the authorities. And if they admit illegal activity to you, YOU should report it to the authorities. If you are someone who is attracted to children you should immediately seek help, admit any and all behaviour related to what if enacted in ANY way is a crime, and if your behaviour qualifies as a crime, you should face all appropriate consequences. Safeguarding the vulnerable is the priority, only if that has been done does getting you help matter.