Taboos around violence for political are one of the crucial building blocks for a functioning democracy. If those taboos are broken, even for a good cause, you set a precedence that violence works. And the next cause won’t be as good. One only has to look at the lessons of the Roman Revolution that started with the murder of Grachus, and ended with an Emperor who everyone acclaimed as they were so tired of the bloodshed.
Violence like that does not work by itself. It only works if you have "legitimate" institutions that are willing to excuse or downplay the violence that occurs.