This is what is simple: people who have demonstrated a willingness to act in a deceitful or otherwise destructive way cannot be trusted, at least until they have demonstrated rehabilitation. Community does not complicate this simple fact.
Exactly - a lack of trustworthiness can be demonstrated long before any crime has been committed.
> And how do you rehabilitate them without giving them the opportunity to participate in the community?
Your use of 'community' in this argument precludes there being an inside and outside, so it is not relevant to the question posed in the article's title. Furthermore, there is an answer - rehabilitation starts in environments where the risk is limited.
Authoritarian liberals seem to forget that what goes around, comes around.
Here's an example situation: you know that a person trying to join a project related to managing money has a history of defrauding employers, starting mlm/Ponzi schemes, scamming people, selling personal information. Do you let them get involved with the project and wait until any problem occurs, because all the problems so far were caused outside of this community?