What causes could people also take a knee for that would and would not be approved?
It is never the simply taking of a knee that is the problem, just like a person getting arrested when walking isn't always merely (or just) walking; sometimes, they're trespassing. When people cry out that someone was arrested for just walking, don't let the fact (the truth) that they were walking be confused with the accusation that they were "just walking."
A person that is sitting may be doing other things. Sometimes, they're waiting, like in a doctors office, which is perfectly fine and acceptable. When someone (on the other hand) walks out of a liquor store and sits upon the ground, they may very well ALSO be waiting, but when they're cited two hours later (and after numerous complaints for bumbing cigarettes) for loitering, don't allow what they think they're merely doing be conflated with what else they're doing.
The act of kneeling is often associated with showing a sign of respect, but not always (as this case exemplifies). What else other than kneeling was he doing? Protesting, and ya know what, that's no more of a problem than is smiling while walking, frowning when running, or remaining stoic and kneeling. What I'm saying is that neither is a problem, so what else was he doing that has so many up in arms?
First, let it be known that not showing respect doesn't always equate to being disrespectful--much like how not believing there is a god doesn't equate with believing there is not a God. One can not show respect without showing disrespect. For instance, while looking for someone in a crowd and not standing for the pledge while not readily a sign that respect is being shown, it's not necessarily blatant disrespect.
This man took center stage to display disgust towards the most precious symbol our nation has.
A white woman on the radio this morning told the story of a black man (a mighty fine man in my opinion based on what she said about him) who talked of how people are too quick to single out the negatives. He reminded us of how things used to be and spoke positively about how there are white people in those stands--people that pay to see the games played regardless of what race the players may comprise. How it was reported was much more eloquent, but the point was that there's a lot of good (and not just bad) that can be contributed to that flag.
If you want to silently refuse to show respect, that's one thing, but don't think for a moment that silent as he was while not showing respect was the only thing he was doing.
The kneeling, not a problem. Not showing respect for the flag; we can even deal with that. And that he was protesting--many of which don't have a problem with, even if some have a problem with the venue. The real disgust stems from the "fuck you America" that the taking of that knee was symbolic of.
Don't confuse walking with trespassing. Don't confuse kneeling and protesting with what he did. Yes, he did both, but just as the guy that came out the liquor store did more than sit and wait, that kneeling, protesting, player did more than just kneel and protest.