EMB145-LR
You mention "the lucky break" and "very lucky minority" in your post. As you'll know in aviation, securing the first job is about timing, networking and (making your own) luck.
Just because you have a frozen ATPL it doesn't guarantee you any commercial flying job let alone an FO position with an airline. As you know there are far more pilots (not just low-houred wannabes) than jobs. The traditional route of instructing followed by air taxi, etc is as hard to break into or over-subscribed.
I receive a plethora of CVs daily from integrated pilots with 200 hours to experienced, type rated, operators with thousands of hours. I have peers that trained before, with and after me that are still looking for their first break and are employed outside of aviation.
I took the plunge and accepted a similar role to this and, after 12 months, now sit in the RHS of a fantastic airliner. Along the way I have acquired knowledge and experience a low-houred direct entrant wouldn't be exposed to. This has helped me (and my crew) in line flying.
A job like this is a great opportunity to break into the business. Jet 2 may offer their apprentices the opportunity to keep current in the sim or by using an FTO. They may also contribute to medical and IR renewals. I don't know as I don't work for them. Whatever is on offer the role is a pathway to an FO job.
If you pass this up in 18 months you could still be in a non-airline job wishing you'd applied. For three lucky (your words) individuals they will be starting in their chosen career as an airline pilot. They will have been prepared to try something other than self-fund to get a step on the ladder. Don't knock them for trying - there aren't many other avenues open.