Everyone is afraid of everything ...other people, sickness, disease, the dark, the city, the woods at night, etc., etc.
They've made alien monsters of good, normal people
Those building employees were not operating under fear when they shut the door and ignored the attack. He is a building security guard, he is not supposed to be afraid of acting as a guard. This was a clear case of indifference, presumably because he is black like the perp. At the very least, he could have yelled at the perp to stop the attack, and then rendered aid to the lady. Those guys are disgusting, both the perp and the workers.