The movie gave a happier ending than the book did.
The guy obviously doesn't fully grasp the Walking Dead situation. People don't "turn" without being bitten; they "turn" when they die. In other words, everybody is already infected and turn into "walkers" or "zombies" or whatever you want to call them when they die regardless of whether or not they were bitten. People who have been bitten "turn" technically when they die -- which may be accelerated from the increased levels of the virus/infection.