Not at lawyer but I believe free speech is not an absolute in the work place. You can not freely disparage your employer unless there is some other protection such as whistle blowing as an example. Just speaking your mind, protesting, etc in the work place is not protected since it is not the public I believe. So the NFL could require, I think, employees or players to stand at attention during the anthem as they could say not doing so hurts their image which it clearly has. But the NFL has chosen not to at this point. I have not watched an nfl game this year and don't plan to. I can live without it.