I'd say that it isn't just a matter of turing that's the mental problem: it's the weight of already being sick. Even if you don't feel the effects (and who knows what those might be long term), the illusion that your body is un-corrupt until you're bitten is now gone.
And I am officially done with Lori. the character is internally inconsistent to the extent that it brought the excellent finale down every time she opened her mouth. I don't blame the actress. It's the writing. What looked like a good Macbeth plot, where she urges Rick to action and then sets Shane up for a confrontation? Apparently it wasn't that at all: Lori just needs to say something stupid and paradoxical in each and every episode.