rej has probably hit the nail on the head when he refers to contracts.
IF the contract says that vehicles will be returned to the contractor is a particular state then it would be quite in order for the contractor ro request that it be done and, if it is not, complain to the CMT. It is not for a civilian contractor, albeit ex-RAF MT perhaps, to demand said sqn ldr, or SAC, to do the cleaning.
Check with the CMT and find out exactly what the MAC says about MT deliverables etc.