Attitude is a very broad brush. Its a combination of attitude and aptitude. Its not so much that they came offf the smaller jets, but more the their approach to the experience.
For better or worse it just didnt click with the way Emirates is geared.
Yes there are pilots down the list that probably are very suitable for the NaC course but they dont have the company requirements yet.
BTW there are no secret instructor notes, those are words from a paraniod pilot.