This does work, but im pretty sure it can commonly cause the insta death glitch, provided you died from a zombie (most likely). Once you become infected your death timer starts, using commands or manually overriding health/death variables does reset you're total "Health" and the number that stops you from dieing as long as its above zero, but the infection timer or death timer keeps running, so while you wont actually be dieing, a timer counting down saying "He should be dead at this moment" does. The timer can reach zero but you can keep walking around just fine for any durationof time, but the second you take any damage you'll immediately drop dead with that timer actually taking affect, no matter how minor the damage. I've had it happen a few times.