Hey PT6A,
Where do you see on FAA.gov beards are banned? Besides a bunch of reports by people named Beard, all I see are an AC that says beards will affect the amount of O2 you from a yellow dixie cup or a diluter demand mask and a case upholding the Captain's authority to bounce an ASI because he had a beard. Me, I would have told the Fed, "Here's your mask, you do this, this and this. If we really do lose the cabin, you're going to be brain dead because we'll be too busy to assist you. You still want to come along?"
All the US airlines require the flight crew to be clean shaven, I've seen a fair amount of fuzz on the cabin crew. It's mainly an image thing, they think the PAX will feel better if they're not being flown around by a bunch of Hippies.
I spent 3 or 4 years hauling cargo in a Three with with a two-three week growth. Just mowed it once a week. Saved I don't know how much time. Finally had to shave one morning in Memphis when I was going to have to ask Delta for a jumpseat home.