Trolling, insulting/derogatory comments, and personal or political attacks
Public or private harassment
Publishing others’ private information, such as a physical or electronic address, without explicit permission
Other conduct which could reasonably be considered inappropriate in a professional setting
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Yes, at least one of those will eventually happen. And when it does, the person should be pointed to the rules and told that they should have known it was unacceptable. What happens from that point is the question.
IMO, if they can't accept those rules, I don't want them around. They're pretty basic, IMO.
If they accept them, but continually violate them, I also don't want them around.