AM, you shouldn't be surprised at Easyjet trying to cut costs when they can, and lets face it, they pretty much can at the moment. Easy were paying golden hellos 10 years ago. Now the opposite is the case. Ruthless cost control (and not just aimed at pilots - they don't pay a penny more for anything than they absolutely have to) is part of what makes it such a profitable company.
However, I don't see why its any more expensive to employ new joiners permanently from day 1. It certainly could be made to cost the same. Perhaps it's an accounting thing.