And we shouldn't allow this concept to go unchallenged here on Lemmy.
Commenting on an active post is not brigading
Posting a link to something is not brigading
Commenting on something you were linked to is not brigading
The only thing that might be brigading, but isn't because it isn't a real thing, is someone explicitly going, "Hey everyone, go here and harass this person"
It's all fine and good that we have some new rules to keep the peace with other instances but we must fight against 
Just to make sure I understand, if they blocked and we left the allow list as is, that would also be the case, right?
Is it just so the other instance can't unilaterally turn federation on and off?
I believe that even if another instance blocked us, if that instance was on our allow list, we coukd still receive updates about that instance from third party servers which include that info in their server-to-server messages (this protocol is the core of how federation works). But I haven’t worked on Lemmy enough to know for sure. That logic can vary between ActivityPub implementations and is prone to subtle nuances in behavior.