I have a guideline...nay a rule for dealing with this kind of thing.
Never, never, never argue with a man/woman with a gun.
Smile politely, thru gritted teeth perhaps, take a note of the time, badge number, physical description of the guard and report the behaviour to his immediate supervisors at the earliest possible instant, IN WRITING.
Don't bother with verbal reports...they are not worth the paper they are written on.
Insist on a written report from the superior.
Safe, simple and gets the point made.
cheers