I think we have reached the nub of the issue here.
The future of RAF FW is an equitable share of JCA plus the Typhoon force. Even to a fishy type that sounds appalling.
So where are the 'Sons of Trenchard' going to get their day 1 fighter from. Answer: A little bit more of JCA - hence RN anxiety.
Why are the RAF anxious? Because JCA is being bought to go to sea. Doesn't really sound like the RAF's patch. (Although they've been there before)
Why are both anxious? Because Joint was a great idea, but actually turned out to be a goat. And the buy is now so small that Joint really isn't needed at all.
And as a parting shot. I have personal experience of the staff environment and the frontline both in the formulation and delivery of JF2000 which became JFH. I don't think it worked brilliantly. You don't have to believe me but my view from someone who 'lived in the nightmare' is that the RAF hierarchy weren't committed to Maritime Strike, and I was personally there when 1, 2 and 4 starred RAF officers demonstrated it in public.