Krusty, having a CPL rather than ATPL does not restrict ICUS on these aircraft, but, having said that the candidate should be undergoing some sort of formal monitoring/assessment which would require the supervision of at least a training captain, i can't see how that could be changed.
Icus was introduced primarily because of this CAO requirement;
8A Conditions on aircraft endorsements
8A.1 For the purposes of regulation 5.25, it is a condition of each command endorsement that authorises the holder of the endorsement to fly an aeroplane with a maximum take-off weight of more than 5 700 kg that the holder of the endorsement must not act as pilot in command of such an aeroplane if:
Civil Aviation Order 40.1.0
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(a) the aeroplane is engaged in charter operations, or regular public transport operations; and
(b) the aeroplane’s flight manual specifies that it may be flown under the I.F.R.;
unless the holder satisfies the aeronautical experience requirements set out in paragraph 8A.2.
8A.2 Unless CASA otherwise approves, the endorsement holder’s aeronautical experience must consist of:
(a) at least 50 hours of flight time as pilot acting in command under supervision in the type of aeroplane concerned; or
(b) at least:
(i) 25 hours of flight time as pilot acting in command under supervision in the type of aeroplane concerned; and
(ii) the successful completion of an approved training course conducted in an approved synthetic flight trainer.
Note
The circumstances in which a person may fly an aircraft as pilot acting in command under supervision are set out in regulation 5.40.
It was never intended as an hour building exercise rather than another arm of LOFT to be conducted to monitor a command candidate in commercial operations. It has now been extended to a lot of other applications and has been abused in the past by GA operators as a means of supplemental income, hence why the hours are discounted by most operators.