Yes, protects, it doesn't require them to. Facebook and its likes volunteering to destroy personal data on request really doesn't have anything to do with the first amendment at all.
Edit: come to think of it I'm not even sure it protects them, but again, it certainly doesn't require them to store or transmit anything.
Edit: come to think of it I'm not even sure it protects them, but again, it certainly doesn't require them to store or transmit anything.