Independently of what the chap actually said, if you're willing to allow him to board him on the condition that he delete a tweet that means either the GA was willing to board somebody they perceived as threatening or they never felt threatened in the first place. In both cases (assuming that part of the story is true) I hope that particular GA gets permanently relieved from the responsibility of making this decision.
And by threatening I mean physically. Just threatening to cause inconvenience by tweeting about you in such a way that your employer can identify you is a bit annoying, but something the GA would simply have to put up with as part of her job.