He's a bully. What more motivation do you need?
But he was a nice fella before this, and suddenly dislikes little guys.
Just wish he'd say "You know, being nice and all made me soft and a pushover, and it makes me sick that Ziggler stole my spotlight at Survivor Series... I went to Ireland when I was healing up and remembered my roots as a Celtic Warrior, so no more Mr Nice fella, and screw these little guys like Ziggler who get all these opportunities and go nowhere because they are too small anyway"
Something to tie in his new look, and motivation.
It just seems really cheesy to have him a heel suddenly, hate little guys, and be a coward to guys like Henry, who were playing the cowardly heel just a few months ago.