Where is anyone demanding a law to force everyone to stand during the playing of the national anthem? The LTE is about running a business. When just over 25% of customers who quit watching the NFL said it was because of a specific behavior, then regardless of what you or I think about it, it's an issue for the owners of the business losing customers.  

Just as you don't see what the big deal is, others do, in a variety of ways, & they, like you are exercising their right to an opinion - they may think it disrespectful, they may think it unprofessional to make a political demonstration on company time.  It really doesn't matter who is right or wrong, it matters that it is disrupting what is actually a private business & turning customers into former customers.  

If a business owner decides he/she doesn't want to hire someone who uses the employer's business and time to demonstrate political views, & thus alienating paying customers, they have every right to refuse to hire.