We already know that JFH cannot sustain support to Op HERRICK whilst maintaining contingent carrier ops capability - that was the reason for withdrawing them from KAF (to be replaced by GR4). Therefore, if you wanted to keep JFH to keep the CV decks "warm", and assuming that we can't afford to maintain 2 legacy FJ fleets, you would have to withdraw fast-jet CAS from Op HERRICK.
Given that HMG's stated priority is support to HERRICK, this must have been a relatively easy decision at the political level. The only alternative would have been to accept that there would be at least a couple of months' reaction time required to withdraw JFH from HERRICK and regain carrier currency for a journey south.
It seems from some of the political statements today that the nature of the carrier procurement (carefully worded "lock-in" contracts, too expensive to cancel, etc) has forced the government's hand. I would judge that this has seriously p***ed the politicians off (Osborne yesterday referred to the carriers as "these things") and probably wouldn't dispose them favourably towards RN aspirations for seaborne airpower.