Gaining/Having the support of the majority of the populace or even being well liked be them therefore making it really dangerous for any action against Twilight Sparkle.

Purging/Liquidating the guilty parties via seizure of land, most of the financial sources and leaving just barely enough for the remaining family to get by and distributing the rest to the populace (in case of the nobles), executing 99% of them and giving the rest a fate worse than death.

Having the protection/backing of a really powerful foreign power RL or otherwise but doesn't have to be a country.

One word: Discord

7063157
If you're putting him in the third part than he doesn't count.

7063974
He can be in whatever part he wants, he's DISCORD! MASTER OF CHAOS! He can be male, female, Q, he can be motherf'n Rick Sanchez if he wants! AND HOW CAN THIS BE? FOR HE IS THE KWISATZ HADERACH! The Force Is With Him, He Is One With The Force.

...Basically, that has been one of my biggest issues with the story, that Discord not only could have prevented Twilight's death, he Would Have. Because if nothing else, she was his main foil, someone he had some level of respect for. Keep in mind, just before celebrating his victory over the Main Six, he looked...regretful, at having hurt Twilight the way he did. Fluttershy may be his dearest friend, but Twilight is also someone he cares about. After all, for Season 9 he put together a team of villains, just to give her the confidence she needed to be a great ruler. Misguided, yes, but still...