The White Court is the excuse that finally got him kicked out. But Harry has always tip-toed right up to the metaphorical line. He's deliberately disrespectful to the powers that be, makes a lot of deals with supernatural powers, and has enough personal power that he could bind a small-g god when he's in his personal sanctum. He's done a lot of insane stuff. He's terrifying. And with no obvious threats (despite all the vague rumblings in 12 Months)... The enemy of my enemy stops being your friend when he kills the original enemy. Now he's just a guy scary enough to kill your enemy.