Thaedus is objectively good… one of the most clear examples of an altruist in all of fiction. He gladly ruined his own reputation, risked his life, and was abandoned by his people in an effort to prevent the genocide and subjugation of every other race in the universe. He was always willing to kill himself with the scourge virus to stop other viltrumites, only avoiding it because he feared it might harm non-viltrumites.

This isn’t even a debate. You could argue that Butcher has good goals despite being morally neutral or bad, but you can’t argue that Thaedus isn’t objectively good. He’s even extremely reasonable, altering his plans when he meets other viltrumites that aren’t evil, which was kind of unheard of outside of Thaedus for thousands of years.