Why not use a navalised Gripen instead of the F-35B?
Short answerIt would need a funded development programme, while the F-35B was the available STOVL aircraft option.
NotesA navalised Gripen would need fresh development money before it could serve as an alternative. In the 2020 STOVL market, the F-35B was the only practical programme available, whatever reservations a viewer may have about it. Procurement choices are bounded by funded programmes as much as by ideal specifications.