Indeed it does appear to be that attempt.
Also, the Met has an interest in managing news in its favour, directing attention away from bent cops (and Haywood and Yates) and toward bent hacks who've betrayed their close relationship.
Once given the story - damned if you run it, damned if you don't.
(The option of running it, with an intro reading "Rebecca B leaked me, in strict confidence, this story about crimes she was responsible to divert attention from her other crimes and she's an evil cow so now I'm betraying my confidential source and thereby setting a precedent that will harm all other journalists in the future, but it's worth it..." is simply too complicated to come up in the middle of a fast-breaking mega-story, I think.)