Good Cop - Bad Cop is when one the (bad) cop offers significant punishment and pain, and the (good) cop offers to help the perp if he will just co-operate with the (good) cop.
Trump certainly isn’t offering significant pain, yet. I see no evidence that Sessions is either.
Ok, maybe the analogy is not perfect, but why doesn’t Trump replace Sessions with someone able and willing to uphold the law on the ruling elites.
Here’s why:
1) It would create chaos and lead to a bloodless civil war on the deep state to prosecute those guilty of crimes among the ruling class
2) It is much easier to let the truth filter out, and eventually the public and the media will move on to other topics