On what basis do you assert that putting women out of harm's way is the reason for a having a nation?
It's called biology. Ten men on an island with 1000 women have a chance at a civilization. 1000 men with 10 women, not so much. Women are biologically more important than males. It's a fact, and any society that fights biology is doomed to failure (in the long term)...
Great question. It's one of a handful of criteria a government must meet to justify exercising authority over a populace. These criteria make a government a better deal than the anarchy of random thugs, predators, and warlords that would otherwise occupy the "public force" niche among us. Keeping order makes prosperity possible and protects the good. The downside is if the order-keepers start to screw up the good we've hired them to protect.
A government we can allow to survive over us is one that 1) helps us protect our families and our liberties by chasing away random thugs and aliens; 2) protects property rights by maintaining laws and punishing thieves; 3) builds roads and such, to promote commerce and travel.
If a state promotes putting females in the armed and protective services, it's falling down in that Number 1) criterion: It isn't taking seriously the responsibility to maintain order, or the reason we value order. In a serious fight against fires, wild animals, or human males, females are virtually useless except as victims. Everyone knows this as a matter of common sense, even if people deny it in the abstract out of politeness or delicacy.
Just as bad as its effect on the competence of the services protecting civil society, the "firefem/G.I. Jane" fantasy undercuts women's justified claim on men to protect and support them. Your average male lout says to himself, "Hey, if women can do anything a man can do, why should I be polite to them, marry them before impregnating them, support their kids, or risk my neck for them?" Feminists make the same argument against normal marriage, usually out of simple hatred for attractive women able to find husbands. In either case, the problem is that women can't do everything a man can do.
Nor can men do the core of what women can do. Only women not pursuing the feminist lie can maintain the concept of home, create hospitality, tend the young, the sick, and the vulnerable, and create a contemplative "space" in society, without which we are all feral. As part of this, they nurture children—who are all the future we have, this side of Heaven.
There are many good, diligent, and even holy women in police or military jobs. But they cannot be warriors in the sense that men can. A government that disdains and demotes our real warriors and replaces them with affirmative-action imitations of warriors—while undermining the domestic society our warriors are supposed to be protecting—is asking to be replaced at best. For whatever reason—whether it's naiveté or evil—such a government is not on our side.