Why not make the intellectually honest pro-choice argument and say that a human life has no more value than the life of any other organism and doesn't really merit any protection other than what it can provide for itself against the other organisms it must exist in proximity to.
If it becomes a pest kill it. If you get hungry eat it. If it's weak killing it make the species stronger and is actually a desirable action. There should be no recriminations for one human killing another if they have superior social rank, strength, or cunning.
Because that's your real argument, you just don't want to say it like that.