But it doesn't make sense. Sure they'd find it extremely useful to have the key, but it doesn't need to be a weak key for it to be useful. If anything, it makes it less useful to them.
If I'm going to ask you or force you to share your password with me, there's no reason I'd ask you to set the password to 4. We might as well agree that the password would be D#!(s9fj0jalk!4af095SF42 , and it's much more likely our collaboration will continue working for years.
"Never attribute to malice that which is adequately explained by stupidity"