I have not paid much attention but i think it is a ramp that rises to hit the hulk not block him, think transformers but wider......

If you look closely it looks like a 3 bank drop target set like on Tron, spiderman and so on. Looks like it will lift the flap up to hit him.

Edit - actually on second look im with you Ant. Blocks the balls. The triangle is not attached to the playfield by the look of it.