If he has to say he is a professor then he is not much of a teacher.
During the Cold war, armed citizens were a invasion deterent.
The USA has more armed citizens than countries with standing armies. The fact we have had orderly power trasitions for (even in the civil war nobody stopped the president from becoming president) for all our history.
Not just the cold war;
“If we were to invade the United States there would be a rifle behind every blade of grass.” Admiral Yamamoto.