Safety from violence is the basic one, and people will often need to make their decisions around it on a faster basis than courts can proceed.
Anti-choice zealots argue precisely this: they are protecting babies from premeditated violence.
It’s not what I believe. But it’s the justification that they use to bomb reproductive clinics and murder OBGYNs.
That’s the risk we run when we accept vigilante justice; we normalize it so that other people can use it for other reasons that we may or may not find morally acceptable.
Society can still evaluate their cases afterwards to say whether they were warranted or not.
Isn’t that what happened here? She was charged with murder, and she took a plea deal since it’s likely she would have lost a court case; she had no reasonable claim of being in fear for her life, and as a matter of law, her attorney wouldn’t be allowed to make the argument that her abuser/victim deserved to be killed.