Players often do drop to their knees in the manner you described, usually as a sign of reverence to something much bigger than they are (such as God, or maybe even just luck) but that only enforces my point that dropping a knee is a reverent gesture, even when it *IS* during the anthem.

I'm not familiar with MSNBC's statement about Tebow's kneeling so I can't really comment on that but I can't think of ANY case where kneeling (in the way you describe) is intended to offend. As for whether kneeling is a unifying act, I would say it depends on the context. On one hand, it's obviously dividing the fans, but on the other it's unifying celebrity with the victims of police brutality.

The unity that I think mainstream media is referring to is the support the NFL has given to the players that choose to express their concern in the face of an openly hostile administration.