If games like Fallout started allowing you to kill children again like the glory old fallout games, would you do it?
We seem to forget that videogames aren't real and even though the world in the videogame is different we try too hard to compare it to our reality.
I've read stories about even games like Dead Space where people refused to kill the alien zombie children/babies even though the babies/children are actively trying to kill you. At some point you have to draw the line between not only fiction and non-fiction. Even so if your real life was threatened by a zombie alien child your self defense would kick in.
I see too many people trying to criminalize killing children in videogames but it's no different than killing an adult in said videogame