Private killing, except in self-defense, is murder (cf. St. Augustine, Contra Faustum, XXII, 70: "In the light, then, of the eternal law, it was wrong for one who had no legal authority to kill the man, even though he was a bad character, besides being the aggressor"). I hardly see why society should laud those who commit this act.
The only harm he caused was taking justice into his own hands. Nothing of what he actually did was an injustice though, unless we are going to start throwing out Leviticus.
He did nothing worse than burning down a porn shop or shooting an abortionist.
A sane society would have already done these things though.
He was picked up as a hitchhiker by a man who turned out to be a sodomite. I have no trouble seeing it as self-defense when he killed the sodomite for propositioning him in an isolated place where he found himself powerless to escape (a moving vehicle he was not driving). Given his history of being assaulted physically and sexually by men in power positions over him, this fear was quite understandable. Ergo, in my view, he did nothing worthy of a conviction in his first offense, and he was defending himself from possible harm.
Druce is in jail because he killed a protected minority who was actually attempting to harm him physically and spiritually, not because what he did was wrong given the circumstances.