Standard NASA budget posturing, imho
Management is under funding pressure, so they threaten to cut some obviously useful and important programme. Suddenly, more money is found...
NASA has fundamentally flawed budgetting processes, where capityal funds are available to build and launch a probe, but operating funds are not guaranteed - often, not even likely, and special requests have to be made in the event of SUCCESS of a probe because suddenly it needs 5 years+ of operating funds that wasn't budgetted for.