@Proper Prose  
Then again NMM is most likely blinded by negative emotions.  
Luna did snapped from how her hard work wasn’t loved anywhere near as much as Celestia’s.  
The shock of telling her she’s screwing up(like comparing her to someone bad, though realistically someone like Sombra who ruled with fear) sure seems to snap her out of it.  
All this needs is some more info(and comparing her to someone else that is more bad that just a simple jerk, like say Sombra) and a better execution in a way.

He’s just an annoying jerk. You attempted to raze the town, violently assialted others, tried to install a tyranny and nearly caused an event that could have kill all life on the planet.
 
You’ll get no sympathy from me.

hot koolaid?

Mad Scientist: “Behold! Using my machine, I have combined the DNA of all the world’s most evil animals! Now to find out what it looks like.”  
(Blueblood emerges from machine) “Surprise, it’s me I guess.”  
Mad Scientist: “You were supposed to be a human. This was a Futurama Twilight Zone bit.”  
Blueblood: “My evil apparently transcends genres.”

 
Riiiiight.

Oh sure, let’s compare some jerk that can be simply ignored to a villain who wanted to force everyone to kiss her hooves after removing daylight forever. Best way to redeem someone is using another character to make the former bad person look better, right?

@TricornKing  
Especially since what Nightmare Moon says here appears to be a bold-faced lie.  

I appreciate the fact that Blueblood is apparently SO TERRIBLE that being compared to him in even the slightest way makes actual serious villains pause their rampages.