If Sessions were part of the swamp, he would have been confirmed by the senate without problems.
This did not happen.
Sessions fooled Trump and many, many conservatives. But as they say, the proof of the pudding is in the eating. After Sessions had been in place long enough to demonstrate his bias, Trump was profoundly disappointed and Chuck Schumer was thrilled and delighted. Schumer going so far as to threaten Trump against firing Sessions tells any honest, objective person all they need to know.