One of the most uncomfortable JW moments I experienced was because of this "don't stand" new light.
My employer was disabled and I was often called on to help him get to various events.
So we go to Santa Anita for the horse races.
He is a member of the swanky Turf Club. We are setting at a table with his friends. The Anthem starts and everyone stands except me and he is across from me in his wheelchair. He looks at me and motions with a head move and a frown for me to stand, I gave him a very small head shake, "no".
Ever get one of those mortified moments when your vision closes down to a dark tunnel ?
He never brought it up later.
As far as escaping from the predicament on a pretense, I think one should use their own judgement. Being surrounded by a bunch of good 'ol boys with a few beers in them might be a good time to go for a pee.
PS I now not only stand but I put my hand on my heart. When the flag is saluted, my voice is loud and clear.