Did Gollum deserve death?

Gollum was a psychotic serial murderer, a traitor & a liar. He was obviously going to set out to continue this if the Elves released him from Mirkwood. Did he deserve death?:-

“Deserves it! I daresay he does. Many that live deserve death. And some that die deserve life. Can you give it to them? Then do not be too eager to deal out death in judgement. For even the very wise cannot see all ends.” (FR I:2, 68–69)

Gandalf thinks not, but he also sees that Sauron sent Gollum out of Mordor on an errand. Gollum was perhaps the first ever prisoner to be freed out of Mordor alive & more or less unharmed. Does this mean he had agreed to come under the service of the Darklord? If so, doesn't a servant of Sauron deserve death, or at least substantial punishment by being locked up for eternity? In the real world Gollum would be put to death.