It doesn't matter how you look at it, the argument is nonsensical. If you lose your old carriers 3 years before the new ones arrive, then you lose the skills to operate them. The press would have a field day if this actually happened. I hear that the RN has talked to the USMC about having guest squadrons on board more frequently. But ultimately, if the RAF doesn't want its Harriers then, give them to the RN.