They're not saying: "Hey, we knew this wouldn't last, but we hired a bunch of people in order to milk the situation for everything we could, knowing we'd have to fire you today. So, sorry we willingly and knowingly did this. But you're fired."
I could respect the honesty in that, but that's not what they're trying to say. They're trying to act surprised by the economic shift. "Oops, sorry we have to let you go."
Of course it was rational for them to all do this. Lying is often a rational thing to do.