Denying everything except the main point is a long established tactic.
In fact, reducing the JSF force could make much sense.
It defuses the RAF "we'd rather have more Typhoons" option.
It reduces the cost of the carrier project in current budget projections, while in theory leaving open the option of buying more aircraft later, or equipping both ships when it comes time to replace the JSF-B.
There are many circumstances (for example, where you'd like CAS and BAI ashore, but there's no direct air threat to the ships) when a smaller embarked force of JSFs would be adequate.
It avoids early commitment to an aircraft that seems to have trouble making it from FW to Pax, much less doing a VL. (Today's question is from Meteorology 101: What is the weather on the Atlantic seaboard like in November and December, and how is it different from the weather in summer?)