As a scientist, he respected the scientific method. Form a hypothesis, test it, and repeat until there was enough data to prove or disprove the theory. Being prodded and shocked by Stark in the confines of the helicarrier's lab was an ill-advised risk for such a genius.
In his head, he laughed though at the pure, absurd brashness of it all, and decided he liked the reckless idiot. A simple poke wasn't enough to bring the "other guy" into focus, but maybe it was time to test a new hypothesis and see what made Iron Man tick.