I'm curious if and How many times a day do you post from work? Positive you and most of us likely do other things on that clock that not directly related to work. This workplace argument seems to be the fallback response "do what they want just not when it annoys us", are you their boss?
Plenty of us have bosses that let us take a few liberties especially when we valued assets to the company. This seems to be a issue for their bosses and nobody else, you seriously feel you in a position to tell someone else what they should or shouldn't do at their job? Their employers don't seem to mind and even appear to encourage it as it doesn't effect their ability to accomplish their job of playing football. The minute the players bosses tell them it effecting their work is the minute they should stop. Just as my play time at work would stop if my boss told me it was becoming a issue and effecting my work.
I'm not pro anthem kneeling, I wouldn't do it but certainly don't care what others choose to do. the only bothersome thing about the whole ordeal is all the damn coverage ruining shows allegedly dedicated to covering football!