When to moderate
From Online Manual
When and how to moderate is a decision each administrator or moderator must make. Some forum administrators will not permit swearing and may modify a post or reprimand a member for foul language. Others do not permit verbal attacks on other members and will delete the post or reprimand the member.
Reprimands may be a public post warning the offending member, a personal message or even a ban from the forums.
In many cases the most difficult part of moderating is attempting to be impartial and consistent.