And what if this manager doesn't care, understand, or act? According to the rule you are not allowed to discuss the problem with your peers at the lunch table. Your complaint has been filed, now shut up and get in line.
I see what they're trying to do, but it's very hard to keep that from being "some astronaut bullshit upper management came up with".
In my experience, professionals don't like to mindlessly complain; it's not their go-to way of attacking a problem. It's what they do to vent frustration after all their attempts at improving the situation have been shot down.
If large amounts of your company are complaining mindlessly to each other, you have a problem with management.
Forbidding unhappiness isn't going to make everyone happy.