I can see that, but I also thought it could be a bioweapon. It is (apparently, judging by how alex got it) an airborn virus that doesnt express any symtoms except in the next generation, so it would be virtually impossible to notice it and react to it in time before everyone is already infected. If a robot wants to rebel, that would be a GENIOUS play. Slowly reduce the rate in which humans reproduce and when they notice something is wrong, finish them off. That way no one would suapect a rebelion until the very end.