My best guess is that my job set it up to force updates that are two weeks late. And since this was the first time I'd booted my MacBook, it was way behind on updates, so it immediately jumped to "this update is so late we HAVE to deploy it now!"
@foone My job does this too, though with a much longer grace period (2 months). At some point it does indeed pop a "System will restart at <datetime>" notification