This ties in with Huxley's philosophy that for the state to be stable, the individual must be stable. Plato's Republic follows similar themes: individuals are chaotic and violent because they do not know what is good for them, and so are damaging to the state. The philosopher ruler must take over, teach people of the Good, and so create a state with more stable, moral men.
Huxley's new world can be seen as such a state, in which its citizens have been conditioned to know what is Good. As such, the individual is stable, making possible a stable state.