Did Gollum deserve death?

[Legate of Amon Lanc]

Originally Posted by Mansun

Recall the words of Gandalf in the Council of Elrond, "I shall roast the old fool over a slow fire". If the ring had been taken by the Nazgul, Gandalf would have killed Butterbur.

I'm not sure if he meant it, as well as I am not sure that even then he would use exactly the method he named. I can hardly imagine Gandalf attacking, stunning and then burning Butterbur (not taking into account that he could hardly do so before the eyes of the townsfolk). Also note that it's Gandalf narrating, describing what he thought at that moment. It may be just "poetic licence" to express his feelings at the moment to the audience.
"Butterbur they call him," thought I. "If this delay was his fault, I will melt all the butter in him. I will roast the old fool over a slow fire."
He expected no less, and when he saw my face he fell down flat and began to melt on the spot.
It is the same way as I don't believe Gandalf wanted to "roast" Butterbur, I don't believe that Butterbur really started to "melt". "Poetic licence", as I said. Also if you look at the context, and take into account whole Gandalf's personality, I strongly disbelieve he would ever kill anyone similar to Butterbur, a simple person who just failed his duty but otherwise is okay. I can even hardly imagine him killing Men. Maybe if he was assailed by a troop of Easterlings, in self-defence, but he did not even kill any Gondorian who blocked the passage to Faramir (unlike Beregond - and not that I would even expect him to do that).