He deserves it if he manages to achieve it. No player deserves a major before they win it.
Exactly, if someone wins a slam then they deserve it as much as anyone else and if they don't win a slam then they don't deserve one.
Djokovic could well win another slam before Murray gets a first, both guys have been up and down this year so it is tough to say which is more likely. Murray has had a few early exits since he broke through to his first final two years ago, I think too much is being made of his loss to Wawrinka.