If the two witness rule is used only for internal discipline I feel it is their right to do that. There is a lot of discussion on this forum and others about how DFing is, so yes there should be a high standard to DF someone. It should be more than just one person who saw someone do something no matter what, because there are false accusations for everything, and yes even for child abuse. If you look at the Irish article that was posted just a few weeks ago there was a case where the authorities couldn't bring charges against the person suspected fo child abuse because there was no corroborating evidence and the only other witness recanted their statement.
Second is in most civilized societies the purpose of prison is not just to punish someone but to keep the community safe and to try and get the person to become rehabilitated. That is why they are called correctional facilities because the hope is to correct someone's attitude and actions. Those who commit child abuse are let out into society and they should be given a right to try and live a normal life. They aren't allowed to work in professions that allow them easy access to those that are vulnerable, but that doesn't mean that they have forfeited their right to live as a human forever. Once they have completed the mandated time they should be allowed to continue on in their life and that includes joining voluntary associations.