MCDU: rather than trying to unravel the FCOM script (ie. written by a frenchman and translated into english by a german!!!) look instead at the flow diagram. This has AND and OR gates and you will see that you cannot satisfy conditions for groundspoiler deployment without either IDLE on the thrust lever positions or selection of one engine into reverse. Thrust to idle during an autoland is an autopilot function via the FADEC and not related to the spoiler deployment.
Regards.