> that is to break the social contract between employee and employed.

Well actual contract is do your job and get paycheck. People try to ignore other stuff you do until it becomes mess.

> In doing that they declared that they alone decide the rules, they alone decide what is acceptable to say and what is not.

Well legally yes as long as they dont brek any law. If you read correctly they consult labour lawyer for their words

> you'll lose your best employees as they decide they don't really want you to decide everything about their waking hours without consulting you

You're honestly exaggerating situation. Nobody want you to consult with them for anything. They expect you to work in office hours.