Its more that “i did it because X” is only a defense when X is something society has written in as a justified reason to break that law. In the case of murder society has predetermined that self defense is a legitimate reason to kill someone and thus it can used as a defense. Killing someone because they are a climate denial activist, they are on the other side of the abortion debate, or any other reason that you personally believe to be a good enough is not a legit defense.

The law needs to be applied as equally as possible and not be subject to the whims of a given judge or jury. Obviously we aren’t perfect at accomplishing this but to purposefully undermine that foundation is a very dangerous thing. It took society a long time to progress to the point that our legal systems are set up to strive for fairness rather than punish whoever the local powers doesn’t like while letting others off because they “did it for the greater good”. Would you support the idea that the state could highlight that these two “did it for climate change” if the jury was likely yo be climate change deniers and thus more likely to find the women guilty due to their political dislike of climate change activists?