I think pre-emptive defederation is unnecessary, but the platform has been live for like two minutes so I'm reserving the right to change my opinion down the line. I want to see how things play out. My biggest concern is lack of moderation.
I'm not of the camp that wants to keep the Fediverse an exclusive club. I want ActivityPub to become a universally accepted and expected standard like email. I want to break the corporate vendor lock-in on social media so that billionaires are unable to completely control the digital commons. This is ideally the first step on that path.
I've had multiple conversations about this across multiple platforms and I've yet to get an realistic answer on how federation could be harmful to the Fediverse, outside of bad moderation. At which point we take the same action we take on any instance with poor moderation. Everything else has been vague gesturing.