I didn’t know there was a Dead Girls Rule. Seems to eliminate a lot of anime, but it does explain the extremist thing (“oh GOD toe-sun will NOT let that go”).
Is it ok to kill boys? Certainly it appears ok for bunnies to wield some pretty heavy weaponry. People of otherwise sound moral character don’t seem to have problems with Tomino’s endless supply of bodies, many of whom are women and children. There’s a real post in here somewhere, not about zaitcev but about … I dunno, consider this a placeholder.