There are many factors which create society's belief that women are valuable and men are disposable. The primary reason is biological. Women bare children. Men cannot.
The lives of women are more valuable because our species would go extinct if their lives were a low priority. It it acceptable for men to be chewed up and spat out and slaughtered in workplace accidents, war, and economic hardship because we basically don't need very many of them.
I think we should be valuing each other, and everyone else in an equitable manner and treat people according to their needs.
Theoretically what you say is accurate, but it's not reality. You'd have to be living in a media bubble not to recognize that the world is still mostly cut on the backs of women and that's the "Truth, Ruth," the whole world over. I think that the statistics around male violence, where the majority of violence committed against women, children and other men, is by other men. In that equation, disposability is not a male feature, except to acknowledge that we have this terrible problem in society where we compel men to be made out of plated armour, deny emotions and any other feminine aspect of themselves. This has resulted in a terrible explosion of male violence that sees wives, ex-girlfriends and in some cultures, their own sisters who break with the patriarchal cultural code, as entirely disposable. I won't go into the common means cause it's all over the news and that's the narrative of the world is it not?
We may send men off to war to die, but the great crimes against humanity are in the raping and pillaging of the rest of the village, that's the women and children, in the name of whatever male defined angry ideology that compels them to confirm their victory over the infidels, by maiming their offspring and raping their women. That's the history of world that i know. So in this way everyone is disposable in war, but let's not forget who is committing those crimes, or who is it that's going on sex tourism, and engaging in child sex-slavery?
I think men have a different destiny on this planet where we stop seeing all around us as disposable and that we learn to use our strength for good, to learn to value each other as whole human beings, and to use our intellect and the positions of power we currently hold to create a more equitable space for everyone. To get there we need to reconsider how we educate boys IMHO.