Well thinking about it, they won't be able to get everyone they need for the summer season online in time due to training capacity.
It makes sense that they would hire a few contractors to fill the gap. We are not talking about a company with training departments as large as British Airways for example, so this is a slow process.
They said 100 slots, so I'm expecting those who can get online with less training(Type rated) to go in first, with some cadets waiting in the hold-pool until end of August/September. With assessments going until mid February, add another two months for referencing/background checks before starting the courses, we are talking about April/May, that's quite late already.
This is simply an educated guess, I have no evidence of this.