Jacko
You may well be right that all CV options are on the table - though the MoD certainly asked Boeing if they could make the necessary changes to the Super Hornet and since they can, it must be in the driving seat.
But as for this being a negotiating ploy, I cant see it. It would have zero effect on the UK getting JSF earlier or getting technology transfer.
This is all about money now, any of the cheaper CV rivals beat JSF on that basis.