Just a point, that some students were there to ensure no one breaks the boycott, and if someone did, these would come in too. So, enforcing the other's decision

Just a point, that some students were there to ensure no one breaks the boycott, and if someone did, these would come in too. So, enforcing the other's decisions and changing your own after see their decision is not exactly Prisoner's Dilemma. Nice mobilization, and nice reactio from the professor too, though.