It says the Browns stopped him. My guess is they just didn't see anything productive happening from giving an interview. It could just piss off the NFL if he says the wrong things and mess with his appeal.
The NFL doesn't like guys airing their dirty laundry. If he brought up the stuff Rudolph did or something with race came up, it could have gotten ugly. If he wants to tell his side of the story, tell the league first and wait for the appeal. He can leak stuff to the media with the Browns help if they think he is being unfairly treated.