While it makes sense to keep
The idea that Twilight could threaten discord is silly and she wouldn't even need to. Discord said that "I'm so sorry it made so much sense in my head, twilight defeats her worse enemies and is filled with confidence, I truly did have the best intentions, I swear I'll make it up to you" therefore he would do it without needing to be threatened. He only messed with the trio to help twilight who is now showing absolutely no sympathy for him trying to be a good friend, while giving the trio all the sympathy in the world for actually meaning ill intent.
He only turned them to stone after the princesses said they would punish them already. He has never shown any problem with characters being reformed who previously have hurt Fluttershy, if the princesses didn't suggest it he wouldn't have done anything. He didn't even go after Tirek for betraying him in s4 or after chrysalis when she ran away in s6 after kidnapping Fluttershy. He has no reason to mess with the trio, if Fluttershy or twilight simply asked him not to he would do it, heck he bowed to twilight in the finale because he was proud of her. I think he's actually being made out to be a bigger jerk and more unreasonable than he actually is.