Of course Redford's piece is simplistic - it is a letter for goodness sake. But there is some truth in his words. For the same requirement for delivering Force Elements you will get more out of an RN FAA Squadron than you will out of an Army or RAF one. due to harmony rules. It was always an issue in Joint Force Harrier and was for JHC when it tried to amalgamate the differing operating stances of each Service...the FAA were always more "available" and more efficiently manned than the RAF due principally to the harmony rules.
We shouldn't be squabbling about this, but we do because of the perceived inefficiency of one Service when compared to the other.
It is a bit like the deployment rates for individuals. When I was serving one always used to see an RAF individual deployed for 4months and 2 days - why? The answer appeared to be that if he/she served for less than this then he/she would not be entitled to the Op Welfare package!