Didn't you?
> if a child has a gun pointing at your head
That sure sounds like defending the killing of children because for sure they were all holding a gun and trying to kill you. Including the babies.
If you show all the YouTube videos in the world, the moment when you find a justification to kill any innocent children is when you become irreversibly the problem.
Your second point literally makes no sense and is based on the straw man that babies are holding guns where I made no point even related to that or collateral kills (which are unacceptable). Secondarily my point is based on internationally legal definitions of combatant and evidenced with a video of combatants being trained. Not like the UN and UNICEF haven't been all over this for decades.
Don't use child soldiers and you won't get statistically significant child casualties.