[vanusa]

Was his flashing the room like that a free speech issue - or a thoughtless dickhead issue?

Independent of his legal "right" to conduct a class in that manner - it's basically kind of asinine to assume your students need to have their buttons expressly pushed in order to appreciate the basically obvious point he felt he needed to make. Or that if people object his resorting to such a stunt - that means they're "offended" by it.