Thats not what the tweet you linked to said.
They said, specifically:
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I know many are wondering about whether you can sell to a 3rd party and still transfer the FSD. Vivian
@Tesla
told me YES, you can do that. So that option is still available to me.
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"Sell to a third party and still transfer FSD" does not = "FSD transfer to the next owner when you sell the car you just got with transferred FSD on it to someone else", which is what point #4 specifically says.