Sometimes traitors can be good. What about someone who was a traitor to Hitler's Germany or a traitor to the Soviet Union because they realized their governments were wrong. Treason can be the right thing to do when a regime is a bad regime. People who betray good regimes for the sake of money or power for themselves are of course bad, but sometimes traitors have nobler motives and are betraying bad regimes.
Basically in my opinion countries and governments as well as other social institutions when competing in an unchecked market can be serial killers themselves. While a traitor is someone who does not conform to a said institution, that they primarily didn't have any choice in being part in the nationalistic sense at least, so really conformity in my opinion when unquestioned causes more feelings of dedication and sanctity then there probably should be. So honestly i if i had to choose between a traitor (who basically is a non-conformist and or whistleblower) and a serial killer (who is either crazy or else in control of their enviroment so that they may silence any oppositions) I'd say serial killers are more morally evil than traitors but monopolizing social institutions are the evilest form of humanity. So morally the individual has to decide but i tend to prefer to treat ethical fundamentalism as monopolizing social institutions, in favor of applying ethical relativism to decisions based on kantian ethics, utilitarianism, and if possible rawls's social justice theory. Of course if individuals can choose to be in one social institution or another in terms similar to free market on the fundamentals im okay with using those kinds of authorities. However if it's like with countries that the term traitior applies to then yeah there probably isn't much choice to be had so serial killers are more evil.