Of course, we all heard what happened to the QF FA that had naughties with Ralph Feinnes don’t we?.
I agree with the OP deciding to write to BA. It is totally unprofessional and I wonder if this FA has done this before. I am sure BA has some type of Code of Conduct for this very sort of behaviour If I was caught doing something similar with a client it would be mean dismissal – it would be deemed gross misconduct
Who would be silly enough to risk their career in these tough times? Maybe the FA was about to face redundancy and couldn’t care less.