Doxxing is very specific-- you are revealing the link between the pseudonymous account and the holder. Elon Musk is a public figure, and posts under his own account.
Additionally, a jet plane, whether private or public, does not have any rights. You cannot "doxx" an airplane. Aside from the practical benefits that ADS-B provides, the public nature of it holds everyone accountable.
Doxxing isn't only for pseudonymous accounts. There are people with actual profiles that use their real names on Twitter and with a little bit of research you can publish all kinds of personal information about them like their current address which can be a real safety issue and would definitely violate Twitter's TOS.
> You cannot "doxx" an airplane.
I think it's pretty obvious that Elon Musks plane will most likely have Elon Musk inside of it. So by doxxing the plane you're doxxing the person. Just think about the same example with a car of someone who may be receive a lot of negative attention, you can tweet out the location of their car and that may put them in harms way. The car has no rights either but revealing the information is still a safety issue. It's just that for planes the data is public because the idea of a plane identifying an individual location is not a common one since so few people own private planes. Another analogy is a bus vs a car. I think most people would be fine with a bus having live tracking and in fact many people depend on that, but for an individual car it doesn't make sense.
Additionally, a jet plane, whether private or public, does not have any rights. You cannot "doxx" an airplane. Aside from the practical benefits that ADS-B provides, the public nature of it holds everyone accountable.