(sigh) Okay, sacha. I guess that's why fighter pilots and military show pilots put themselves through such rigorus lowerbody/upperbody muscle training... so they can have a harder time withstanding G's. By your reasoning, we should looking for midgets to pilot our fighter jets.
It's great that a 5 foot tall person can withstand G's better than a 6 foot tall person... that is, IF they both had the exact same amount of muscle mass.... say 60 lb. I can see where you're coming from. FOr instance, if someone's head wieght 15 lb and another person's head weighted 13 lb., and they both had the same amount of neck muscle to hold their head up, the person witht he lighter head would be able to hold their head up longer under G-force stress. But that's not the way the human body works. The bigger your body, the larger your muscles are to support you.
Women do not have even 40% of the muscle building capacity that men do, and the more muscles your body has, the better your circulation, the better you can withstand G-forces. So if you took a fully developed female and a fully developed male, you would have anywhere between a 40% - 60% disparity between the two when it came to withstanding G-force. I don't see what's so hard to understand about this.