Political violence cuts both ways. I don’t think anyone thinks what happens to politicians go against the cartels in Mexico is good or healthy system. For democracy to work we can’t have people constantly fear for their lives. Sure Trump is a terrible human being but I don’t want my candidates living with the same fear. So our only choice is to condem it. Also when bad acting becomes the norm bad actors will thrive. If political assassinations becomes the norm do you think morally justified “good guys” assassin going after Hitlers are going to win/out pace organized crime like what we see in Mexico?
At the end of the day ends don’t justify the means. Violence breeds Violence. In this modern age if we want to create a peaceful society we have to do it peacefully. Violence might be an appealing means to an end and while we might have the moral high ground but they use the same logic to justify their violence.