seeing as the police asked you then the answer is pretty clear, to preserve evidence and to preserve law and order in its correct domain - not on the streets.
Why on earth would you think that reducing speculation is anything to do with a defence barrister, its not the job of the police to aid the defence is it. If you are talking about yaxley his speculation was not legal, he literally judged the defendants and mocked the court whilst in was in session and tried to get his opinion on guilt out here to prejudge the jury. Like it or not we have trial by jury, why on earth should the not be allowed to do their job without a little twerp suggesting that they should be done over if they acquitted the defendants is beyond me.