Pilot Competence?
When looking at the suitability of the occupant of the right-hand seat to occupy that position, I should have thought it prudent to ask yourself "would he/she be able to land this aircraft SAFELY in the event of my incapacitation?"
It is not just a question of economics, but fundamentally about the requirement for a two PILOT cockpit. Whether the individual concerned had the aptitude/training or experience to adequately fulfil the duties of PNF, it certainly does not appear that he/she would meet the criteria of the above paragraph.
Personally I think we are compromising proper training and the experience that these low-hour cadets really need just for the sake of a few months and a few more pounds.