I can't imagine there was any sort of plea bargaining, other than the advice from his own lawyer that he plead guilty or face tougher penalties. 100+ witnesses, recordings and a wrestling match with the plod, he's not got much to bargain with as they have everything they need to prosecute. It's not as though he would be able to 'rat' out another possible trouble making passenger as a chip, maybe he told where the in flight cookie was buried, or are they becoming organised, should they send him out with a wire?