You don't go into KNOWN icing in a 172, but casually finding it isn't a death wish. It requires some action on the pilot's part, which is my point... Also, he's the instructor and and the PIC.. his call... (I'm an ATP with over 5k hrs, but wanted to let him run his cockpit.. I just needed the check in the block). His panic was from never seeing it before.. Lack of experience. It's simple enough.. if you get into it, get out.. A simple call to ATC or just do it on your own and explain later. Either way.. my point is, it was his plane. His situational awareness was non existant and his ability to calmly react to the situation did not exist. Trust me, the situation wasn't dire.. If you think some light rime on a spring day going in and out of the clouds is terrifying conditions... you haven't flown in the Northeast much. I was told he was one of their better instructors before the flight...