Rant Time  
I feel that people don’t quite understand how redemption works. Let me start with Vavacung’s series with the changeling. In it, Flurry attacks and almost kills our main protagonist. The thing is, she has been taught that changelings are evil creates that attacked her parents and use them for food, yet try acts like she tried to kill a baby. She went overboard, yes, but she has reasons, and saw someone that threaten her father, and may have enslave her aunt’s kingdom.  
Now let’s talk about this one. Part of why I love Celestia is that she had the courage to stop her sister from enslaving her subjects. She atoned for her sins/mistakes by doing the hard decision and stopping her sister. Here, she’s taking the coward route and letting herself die and her subjects suffer all because it’s hard to pull the trigger.  
Redemption is working to correct the mistakes you made, not accepting punishment from the one that’s trying to kill you or from people that overreact to what you do, especially when they would know the reason for your actions.