Effectively, by ensuring PA dont get any financial penalty through a desk posting, surely what they have created is a scheme whereby Professional Aviators get to sign on... To sit behind a desk
And lets be realistic about this, if you have some young shag flt lt at the end of his first tour, wife is pregnant and about to go on a single salary, with a mortgage to pay, what is the deskie going to do once the Flt lt first tourist explains to their flight commander they cant cope financially?
Yep, you have guessed it, find a suitable PA!