Tesla then needs to refund the original owner -OR- if the original owner buys a new Tesla, FSD should be included for free -OR- FSD should transfer with the car. Otherwise the original owner purchased FSD which was never delivered before the car was sold. Then even the potential for FSD on that vehicle was subsequently removed by Tesla. If Tesla wants to claim that the rights to FSD are with individual and not the vehicle, then they need to include FSD on every Tesla the owner may purchase in perpetuity, because that individual has paid Tesla for it. If this is the case then I have no problem with Tesla disabling FSD for an owner that never paid for it. However, I doubt this is the case. I suspect that Tesla wants to have its cake and eat it too.
Honestly, I'm generally a huge Tesla fan but the company does do some really scummy things and this is one of them. I personally would not purchase FSD unless it reaches at least lvl 4 capability and can basically drive you door to door on it's own outside of the worst conditions. However, considering that could take years and apparently will be disabled if you transfer ownership of said vehicle anyway, why would anyone choose to give Tesla $8,000+ for an option that's years overdue, won't add resale value and probably still years away?