Ultimately I think there will have to be a legislative solution of some sort (sadly). After all, if you bought a used car from a dealer, and a week later, someone from (say) GM turned up and pulled off some parts and took them away, you would be (rightly) furious. Similarly, then if a car has a software option on it, then, yep its on the car for good, unless Tesla take ownership of the car and adjust it before resale.
Tesla no doubt will try to treat the software stack more like retail software, which you never technically "own" in the first place (what you own is a restricted license to use the software). But I dont think that will fly long term.
The thing with software is its a license to use the software, not the actual software you are buying.
Tesla really just needs to fix their process so that this doesn't even happen (FSD removed before being auctioned). So many issues with Tesla come down to communication and broken processes that take WAY too long to fix, even though they pride themselves on being agile.