I attended college during the Vietnam Era. It was common to have anti war demonstrations on campus (I attended an urban private university in Boston - no, not Hahvahd). We also got the occasional bomb threat.
As engineering students, we didn't cut class. Trying to catch up from missing even one lecture was not worth the trouble. One day we were all in a Fluid Statics and Dynamics lecture when the word was passed that the building had received a bomb threat. The professor stopped the lecture, looked around the room and said, "The walls here look pretty substantial. I am going to continue the lecture, but feel free to leave if you want to." Everybody stayed.
STEM students don't have time to demonstrate.