The short version of the truth: The original owner did not buy AP. AP was enabled because of a bug. The dealer listed it as having AP included because, at the time, it was enabled. When ownership was transferred, the glitch was corrected, and AP was removed.
The new owner bitched very loudly to the press, and Tesla restored AP to the car, for free, even though it had never been paid for by either owner.
It has nothing to do with FSD, and nothing was revoked because ownership changed.