According to official JW theology/doctrine type fantasy bullshit, it goes like this.
Universal Sovereignty.
You see, mass genocide will turn out the best way of doing things and it will ultimately reveal the infinite wisdom of God. His love and justice will shine through, and his right to rule and his claim as 'universal sovereign' will be unquestionable.
And in case it is questioned the universal sovereign/tyrant will quickly execute any who don't follow the strict regime of gruelling daily worship rituals. It's called 'Paradise', perfect seasons all year round. Strictly no clothes and technology, because the Universal Soveriegn has a history of getting volatile and letting his rage take over when humans get overly ambitious. It's that genocide thing, it crops up from time to time with the Jehovah.
But at least we will have settled the sovereignty issue, because that's the real issue after all, Universal Sovereignty. Just ask a JW about this universal issue of extreme importance, they will teach you.