Stitching you with acting rank I can understand, just one of the ways that Manning have to get you in the end.
I struggle to see how they could post someone to an HQ & argue that the job was 'flying related'? Ultimately any job in the RAF ostensibly contributes to the role of the service & could therefore be deemed 'flying related' but the fact that they have differentiated 'flying' & 'non-flying' would imply to me at least (simple soul that I am) that the former must directly be related to the aviation task. Sim instructor? Ok. HQ Staff wallah? Not ok.
To fill Staff jobs with PAS Flt Lts would surely go against the purpose of expensively retaining experienced aircrew?