What is the actual risk? I suspect he's way more likely to get into a car crash.
The information about his plane's location is already public. Posting it to twitter just makes it spread further. Also, a plane's location isn't very useful. Even doxxing someone's permanent address (not that elon has one) is a pretty minimal threat to their life.
A plane's location is some of the less dangerous speech allowed.
It should be obvious, but to a crazy person who is interested in harming Elon, this is a gift wrapped up under the Christmas tree. Great, now they can wait outside the airport, or know that he just flew home to Austin tonight, or landed in SF to go to Twitter HQ. Nobody would know what jet Elon owned if it weren't for that account.
The information about his plane's location is already public. Posting it to twitter just makes it spread further. Also, a plane's location isn't very useful. Even doxxing someone's permanent address (not that elon has one) is a pretty minimal threat to their life.
A plane's location is some of the less dangerous speech allowed.