In this case it's pretty specific to someone wanting libelous information removed. If the analogue is a print publication having to retract something it is (almost?) always after a judge has looked at it. If Britney Spears suddenly considered everything ever said about her libelous she would have a tough time convincing a judge of that i would say. Just like celebrities usually have a tougher time getting things retracted now since they are in the public eye more than Joe Average by default.