Why Force Z had no clean withdrawal

What should Force Z have done once it was already at Singapore?

There was no clean withdrawal; the strategic commitment had already trapped an inadequate force in a mission it could not abandon without destroying its deterrent purpose.

The decisive error occurred before Force Z reached its exposed position. Once Britain had sent capital ships as a public deterrent, simply withdrawing them would destroy the diplomatic signal and contradict centuries of naval expectations. The commanders had to operate with the inadequate force they possessed rather than the force strategy required. Deployment choices had already removed the clean tactical options.