Just Maybe
The Explanatory Statement to the Amended Regs specifically refers to the loophole, expolited by some, that allowed a person not ordinarily authorised to be on the flight deck to enter before take-off and exit after after landing and claim the regs were not being broken.
Is it possible that if everyone had complied with the intention of the previous regulations (i.e. just allow employees on the jump seats) then the regs would never had to have been ammended that closed this loophole and further restricted the use of jumpseats.