I don't like companies that think they can control what their employees say off the clock. My company has moved to do the same things, which has led me to stop posting on PFB as much as usual.

I don't post confidential information about my company because that's no one's business but ours. Other than that, I feel that it is within my rights to say and post whatever I feel like.

It sounds like you might be mad because an "employee" was rude to you. You do not have anyway to prove that those are really employees.

Complain to the admin of those websites, if they have any.