Not qualified = not in command.
Bingo. Until you have a sticky in your book for that type (if req) you are NOT qualified to command, hence no ICUS is permitted.
Back to ATO country,
From the ATO Manual
Pilot-in-Command: The ATO is the pilot in command when occupying a control seat.
Applicants will log dual for all flight tests except when undertaking a CIR renewal. If the
applicant is the holder of a CPL with current CIR and meets the appropriate recency
requirements, the applicant may log ICUS. When the ATO occupies a backseat/jump seat,
(in a mentoring role/observing role), he is not the pilot-in-command.