I wonder how this reasoning applies to human foetuses ... If the argument that killing is a necessity for free-er sex is judged to be moral, then how could you

I wonder how this reasoning applies to human foetuses ... If the argument that killing is a necessity for free-er sex is judged to be moral, then how could you possibly judge against someone killing for survival ? Hell, how could you possible hold killing for fun against someone ? (not taking a position, just pointing out the massive inconsistency)