We had a thing a while back on Lemmy where a bunch of semi-popular instances (including lemmy.world, though they seem to have rolled that back) all defederated from instances that mentioned piracy. I don’t have a problem with piracy. I want to talk about piracy.
To me, that is a feature, too. The admin team made a decision, and the community engaged, the topic was discussed, and the decision was changed. To me that's a very healthy process. The only thing I would've changed would be LW engaging the community before defederating, but they were understandably worried about legal implications.
Even if LW didn't reverse this decision, you can change instances. Lemmy 0.19 makes this easier with import/export, but I would argue it should be even easier. Ultimately though this is a lemmy implementation detail, and not an activitypub problem.