Unfortunately, Charter is well with in their rights to do this. It's called At-Will employment. The only thing that could have stopped this, is if the workers worked under a collective bargaining agreement. Even then, it would be hard to stop. But, it would have at least made it where Charter would have had to bargain the new rule. When you work AT-Will, the company has the right to change anything, at anytime.
This is CABL.com posting #288274. Tiny Link: cabl.co/mbm9K