Sasha always wanted to be married with children, Erwin did but didn't want to leave a widow behind and certainly didn't want his children to be orphans. The funding for the Scouts will stop if Erwin doesn't marry. It's ridiculous and will prove nothing, it won't bring any fallen soldiers back and will end with more mouths to feed, more hearts to be broken, and more orphans if Erwin and Sasha ever perish.