Clearly the VC10 will not be the only ac in the military inventory to be reviewed in the wake of the Nimrod enquiry (standby C130K fleet).
If I remember correctly, the infamous QinetiQ Nimrod report made it clear that similar problems in VC10 were discovered before Nimrod - around 1996 I think. Action was taken on VC10, but not Nimrod.
Perhaps this explains the "early" decision - other fleets may take longer but information on VC10 is reasonably up to date. I'd say, well done to that project team. Difficult decision.