Having worked in pax handling myself in my early aviation days, before I moved into engineering, I can confirm that Magic Buff's idea about the 9.5 foot 200 Lbs gorilla works.
I had a very bad situation once in the arrival gate I was responsible for, with lots of drunken German PMI passengers and a huge delay in them receiving their luggage due to an unexpected snowfall, which forced the handling company to move half of their loading crews to de-icing.
I'm not a short@rse myself, but it really helped to have a loader of said 6.5 feet, 200 lbs of pure muscle and hands like frying pans standing at my side, giving the crowd a happy grin with his missing front teeth, broken nose and cauliflower ears (this guy looked like a professional heavyweight boxer)
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People, who were previously very agressive, just had a look at him and became very polite.
I've seen the same at our airline. We have a few male flight attendants, who are into bodybuilding and if they are on board, even with our Morrocco flights (where many male passengers refuse to take orders from female cabin crew), there is normally no problem.