In general we have laws against tracking individuals.
What he does seems legal but it doesn't make it good or ethical.
FAA didn't create a plane tracking system so that a kid can put this info on a map in real time. It's a legitimate security risk for those planes and people who use them. It's an abuse of the system.
In fact it's not even Musk's plane, he just owns the company that owns the plane, Falcon Landing LLC. The twitter account didn't actually know if it was Elon Musk being flown or a bunch of burros being ferried back and forth between US states.
>FAA didn't create a plane tracking system so that a kid can put this info on a map in real time.
You're right, the FAA made the system open so that anybody could do this, not just this kid.
Freedom of speech has to come with some caveats or its dangerous as it can be used as a weapon.