While I do not endorse the tactic of not standing for the National Anthem, the Steelers management may have hit upon a compromise solution.
All the players who cannot or will not participate in the flag and anthem ceremony for SJ reasons will remain in the locker room until called on to the field. That way their “conscience” is honored, they are denied the opportunity to stir controversy through their actions, and there is no photographic and video record that entangles the team brand in the issue and possibly suggests, rightly or wrongly, that team management endorses their actions. If a player, without intention to deceive, wants to take the field to honor the flag and anthem, they can.
Basically, if you wear the team uniform, you are expected to model behavior the team approves of. If you can’t, then you are not authorized to be on the field until the objectionable portion of the game is over. And the hammer to enforce this is their contracts and the power of the team management to impose fines and penalties on any player who does not obey
Villanueva is going to face criticism from his team mates, the sympathetic liberal/left press, and the SJW crowd. Being a US Army Ranger and a combat veteran, I am sure he can take the heat.