Sessions as ninja is an appealing idea, but there is nothing close to actual evidence that he is. That’s why the bizarre belief that Swamp-draining will be done by the military; no one believes the DOJ is pursuing such a course.
The most damning evidence that he's not a "ninja" of all is the fact that so many on the left, the media, and GOPe defend him and threaten Trump not to fire him. If he was anywhere close to going after treason and sedition on the left, there would be a very active campaign to destroy him.