From what I've seen, Norwegian tends to recruit the most experienced candidates.
For instance, I do not know of any cabin crew that has been hired without previous airline experience ( outside Scandinavia that is).
With such a response for the NTR position, I can only imagine that they are looking at all possible ways to shorten that list. And I would think that experience would be a good place to start.
I don't think age would play a part considering some of the best guys I fly with are past 50.