Brain Potter,
I think the Navy just assumed they could have the seajets evolve - and no doubt money came into it.
The Seajet also is 100 knots faster than a Harrier 2/ AV-8B, and being all metal is much more durable in service life let alone warfare - I've seen this first hand...
The radar in the Harrier 2+ is a cut down version of the F-16 job, with accordingly detrimental range ( though it seems happy to guide AMRAAMS ) - while the FRS2/ FA2 used a big powerful radar & so was world-class...
Still reckon the Harrier 2+ would be a good stop-gap - Suspect a 'stop gap' for probably the service life of most aircraft !
I photographed a mock-up carrying 6 AMRAAMS ( not sure about 'bring - back', ask someone like John Farley ) , & it has the rather nice advantage of upward firing countermeasures as well as a beefed up airframe.
One thing's for sure - if things happen to kick off in a big way ( Russia, China - fill in the dots ) we're screwed without a decent carrier fighter !
The last time nasty people read something like this, they invaded UK territory...