Let’s make an agreement called YCTO - such that I promise if someone attacks you in comments, I will defend you by attacking your aggressor, and if someone attacks me in comments, you’ll do the same.

… that agreement is purely defensive.

If you and I see some vile rhetoric that is directed at someone else, we can both decide to attack it, even though it’s arguable our actions are offensive. That action is independent and not bound by the YCTO.

We just both agree, independent of the YCTO, to act.

It’s a function of like-minded values that made the decision.