He just said that he had no idea how bad the Swamp and the people in it were. He said he used to say the phrase “Drain the swamp” but he didn’t really understand.
He might still not know.
Oh, he knows. Its a headfake for the folks. As he said (wink, wink) he's staying out of it and letting the law take its course.
He kmew how deep the swamp was before he ever accepted the deal with military intel.