Zimmerman just got saved from a vicious beating.
Z’s former self-defense teacher said he was a weak puncher, soft and virtually unteachable.
Maybe, foolish as it is, he figured if he let the biggest blackest guy he could find beat the crap out of him for all to see, it would be taken as penance and sate the bloodlust a bit. Not saying I agree with it or think it would work, but...maybe that was the reasoning.