Nah. My guess is only a few of the Steelers actually wanted to take a knee, but the powers that be thought it might be best for the whole team to stay in the locker room to avoid the entire situation.
Well eventually they are going to have to come out unless they plan to hide out forever.
The rule ought to be that anyone who doesn’t want to stand for the anthem must return to the locker room for its playing.
Everyone else can stay.