Anecdotally, ARIN has, in the past, gotten involved in this sort of thing.
Many years ago, during an acquisition that went sour at the last minute,
the renegging seller went to ARIN complaining that we were hijacking his
IP space. ARIN contacted our upstreams and pressured them to pressure us
to stop advertising the IP space. Perhaps there's no official policy, and
perhaps they wouldn't do this today without one?
I would argue that action without an explicit official policy that outlines the circumstances under which what action is taken is just asking for awkward situations to arise.
- Matt