The micromanaging never ends  

Maybe it was someone else who did something and the guy doesn't want to single him out and sends an all hands message? One possible explanation, but I have no context.

Another might be that his boss said tell crews....

'maybe there's a common mistake folks are making, and you're not one of them...but others need the reminder.

micromnaging, for a pilot, would be something like being in the cockpit telling you which decisions to make. An email is just annoyance management.