If the forum software has modern access control, then any of its objects should be governable via permissions.
Via access control, could moderators:
-- prevent two or more participants from addressing one another for a cooling off period, or
-- prevent access to the thread in question for those in heated dialog, or
-- put the afflicted posts in a private msg and send the perpetrator's there to finish their disagreements
-- and other options.
(Hint for KeithR: mediation)
There are lots of ways to address conflict beyond the heavy-handed protocol the owners/moderators adopt. Warn-and-wait for compliance then suspend/ban is crude, people being people. Unless the aim is humiliation or punishment. The conflict in this issue is long forgotten, but the consequences of how it was dealt with will be here for a long time. Time to look for other ways.