It's not the law you have to think about. No contract that will not allow you to persue employment in your vocation would stand up in court. It's all about the relationship between your prime and the MSO. If the MSO wants you in their system the prime will just have to grin and bear it if he wants to continue making $$$.
This is CABL.com posting #158136. Tiny Link: cabl.co/mPiK