How so?
A happily paid worker with their own free time isn't likely to revolt and kill you. Even an unhappy worker who hates you will just quit. Is your calculations forgetting to count such costs?
And a machine that replaces a person is far far more efficient. So machines backed by human operators/fixers/etc. end up outperforming humans, and free humans will have far better education possibilities.
>From an economics standpoint there is no point to the elderly they should be killed off once they are no longer viable laborers.
You are clearly zeroing out the cost of having all non-elderly realize this will be their fate as well. That seem an arbitrary cost to zero out and makes the results of your calculations unusable.
>Children are only useful if they show potential slave labor ability
A free child that is educated has a much higher return on investment on average.
>otherwise should be killed in adolescence if there are obvious shortcomings
Once again completely ignoring the costs of taking such a course of action.
I'm not really having any confidence in your models.