Flt Lt PAS can only be employed in 'flying related jobs', which whilst that definition could be interpreted fairly liberally still restricts them to a flying station.
Sqn Ldr PAS however can be employed in 'non-flying related jobs' so yes, they can expect to be routinely occupying staff jobs. A discussion with the current poster some time ago ndicated that Sqn Ldr PAS can expect to be in a flying job roughly one tour in 4 as I recall, so your acquaintance's experience would be about right.