Because they have nothing to fall back on and they are not in control of the situation but are responsible for the situation. Corporate eunchs, responsibility without power. The project is a disaster and everyone knows it, there will be a fallguy when it burns to the ground. So they melt down. Try to control the one thing they can.
I get it, because I have seen my project managers over the years in the same position. Of course they start screaming about coffee breaks, they are looking at unemployment. It’s a shitty situation.