She was the one not following the rules

All he did was sit there in a seat, then walk off the plane

He was not required to stop his forward progress and turn around just because someone says sir behind him - what if he was busy or in a hurry

Also, no American citizen can ever be legally compelled to wear any object across their nose and mouth just to suit someone's idea of their medical safety

And businesses violate US Code if they refuse service to someone for refusing to cover their nose and mouth, forcing them wear something that has even a small or slight physical effect on their breathing, for any medical reason; it is practicing medicine without a license.

It's as illegal as posting a sign saying you can't get on this plane if you walk with a limp or have asthma or a cold. They aren't qualified to diagnose your medical condition.

A stewardess crying could be having gas, PMS, too much stress, just broke up with her boyfriend, etc., etc. The guy didn't abuse her IMHO

She was the one not following the rules

All he did was sit there in a seat, then walk off the plane

He was not required to stop his forward progress and turn around just because someone says sir behind him - what if he was busy or in a hurry