Maybe killing them is too inefficient, we could still put them into forced labour and squeeze some usefulness out of their life but with automation taking over, probably not.

The “red flags” you refer to are just knee jerk reactions you’ve developed after being told that any deviation from the opinion that all human life is equal should be regarded as heresy. This is ultimately just an overly-liberal opinion that was taught to us in school as fact. Not all opinions are equal, not all minds are equal, not all lives are equal.

When you murder or rape with no sign of remorse, the value of your life drops significantly and you should be treated like dirt accordingly.

The idiot in the article, he no longer deserves to have a good life or to be happy. If he spends the rest of his natural life in a state of misery, locked away from society, justice will have been done.