Ah, let's do this again.
ALT SCENARIO 1: This time, unbeknownst to the "attacker", the student with the gun passes it to another student in a different part of the room.
ALT SCENARIO 2: This time two (are more) students are armed, while the attacker only thinks one is.
ALT SCENARIO 3: We go to the local jail and ask inmates if they would attack knowing that about half the class were armed? If 25%? If 10%.
ALT SCENARIO 4: (for fun) All students are armed with paint ball guns and have them ready. The attacker is lead to believe only one is CCW as in original scenario.