I'm sort of conflicted.
It seems that such matters should be as public as possible. I pay their salaries, I have a right to know what is happening when such a matter comes to termination. Bad cops don't get to keep these things private when it comes to serious dereliction and outright lawbreaking. He's not publically admonishing a rookie for forgetting his tie, he canned cops who got arrested driving drunk and who capped surrendering suspects. Its the kind of thing that should be posted in the town square. We rely on the news on television and the internet for this right now.
The one with the domestic might be on the line, and the dereliction thing is iffy. The shooter and the drunks deserve no protection.
Morale in the DPD is a flat zero already, and the public trust is iffy in a good neighborhood. He'll get a dead cat bounce if nothing else.
I give him a D: Ok idea, poorly thought out, poorly executed. Net gain, but only just. Twitter is not the right medium, IMO.