From my perspective there were equal numbers of experienced FOs and Cadets throughout the interview process and then selected for the job.
FOs hours ranged from 1000 hours multi crew to 2600, the range of experience for captains was massive also.
I don't think at any time the fact that cadets were being recruited was hidden, as the recruitment was for fleet expansion then it makes perfect sense to recruit a wide range of experience. Why recruit only experienced FOs who might only feel way down the seniority list, years from command at the point they feel ready for it.
Having people who won't leave for 4 years and are keen to build hours and loyalty to an airline, compared to someone looking for a fast track or just jet time on the way to their next job is forward thinking.