The only thing I can think of is two fold:
1) He was never accused of fucking a minor but hiring a prostitute (who was legal age).
2) Given his knowledge of the activities with that cabal and his proximity to see and hear many things he thus becomes a good situation to know where the would be bodies are buried.
Sometimes to clean house you must use something that you would rather not but still do so because it is the best option at the time. In this case and given how easily people tend to disappear or commit suicide by shooting themselves with a bazooka to the back of the head I think it makes sense he would be brought in under the guise of "working with" when in reality it is merely information acquisition for the true targets. Bypass one small thing to allow the door to open for what matters. Very normal in the justice world.
The media cannot openly attack him or they would be openly attacking Clinton/DS. So they are forced to wait and see which sidelines them and at the same time assures all pressure flips to the true targets of investigation because now that they see he flipped they will know, without a single doubt, that he plan to chirp and if he chirps, they go down. I expect to see a massive FF or worse very soon from them in response unless Trump has neutered their ability to do so. In the continental states, he undoubtedly has. Therefore I expect this FF to occur elsewhere, likely the EU due to the fact there is so much presence in the Middle East at moment, Asia is out of their line of control and the masses typically do not care about Africa thus making EU the likely spot for misdirection.