I like that.

It sounds very abusable. Would it need timing safe-guards (invalid if time since last rotation is below n seconds)

A potential danger is if an attacker uses that event. Then your followers are transfered to an account you don't control away from the account you control -- and someone else isni charge of your presumed identity. The benefit of current situation is that if the attacker figures out your nsec, then at least you got equal access to whatever followers you gathered and can send warning messages about the attack. Possibly even send signed messages to your followers if you have some other well established crypto key pgp or similar that they trust.

Addition: these things can't be done automatically as the follow link is stored on the follower. They would need to sign a change to their follow list for it to happen. There could be a suggested follow event though, that the follower need accept and sign manually.