Wither "boxing" Melee Attack

When I first summoned the wither, it looked as if it was trying to punch mobs with its heads, which looked like a really awesome attack. To my disappointment, it turned out to be a pathfinding quirk that didn't actually do anything, so I propose to turn this illusory headbutt flurry into an actual attack. If any non undead mob gets too close to the wither, it will agressively spin and headbutt the target, causing 8 damage per hit (16 DPS), and a sweep attack that causes major knockback to all nearby entities. Imagine fighting the wither, and mid fight, the wither throws a flurry of punches to keep you off its back.