See, that's what I was thinking, but during State 1 the virus hasn't fully taken over, implying that other organs are vital to the subject's survival. Stage 1's are still "alive" per se, but Stage 2's are completely dead aside from the brain. That, and it would make the zombies a little more dynamic. Stage 1 favors speed, though they are weaker, while Stage 2 favors resilience, but are much slower. Also, and the added splatter effect from the still-circulating blood present in Stage 1 would allow them to distribute the virus more quickly to really get the infection spreading. Just my two cents personally, I'm really down for whatever!