As mentioned above, you own the knowledge base and let your customers use it, but everything that takes place there should be on your terms. To prevent situations when some customers constantly act in a socially unacceptable way, are rude, or start arguments, create a list of behaviors that won’t be tolerated.
When creating knowledge base terms and conditions (or however you will name that list of do’s and don’ts), highlight specific actions that will result in moderators intervening and, in the most difficult situations, in temporary bans or customers being removed from the forum. Do everything you can to communicate these rules to customers before they start using your knowledge base, then just make sure users follow the rules.