Anyone who has studied any economics (aka, not liberals) knows that price controls just don't work. They sure sound nice (who wouldn't like to have no price increases?), but they end up being counterproductive to their stated goal.
All this will end up doing is driving these companies out of business (or at least out of that part of their business) and making it another government monopoly. So, they are starting with Medicare Advantage. Just wait until the government puts up price controls on your company-provided health plans. Don't worry, that's in the works, too.