I'm not debating that - I think you're right. Then if the employers "crumble" so be it. No different than our jobs - the best employees have far more influence.
However if Brady, Gurley, Newton and Rodgers go to a baseball game - they can use the bathroom during the anthem if they want to and wear street clothes. They can also stand with their hands on their heart during the anthem at a baseball game and if they don't like that some baseball players are kneeling, they have a right to not like that as a customer.