There was a time when I did assessments for recruitment, I never scrubbed anyone in the LHS doing the PF part. It held almost zero interest for me. Far more interesting was to assess the person doing the PNF support functions from the RHS, quite a few were scrubbed.
A novel assessment policy indeed - but horses for courses. However, it is often the case where there are just the two people in the simulator - the testing officer and the candidate. Under those conditions the testing officer will operate the gear, flaps and MCP panel on direction from the PF. There are no support calls since the LH seat candidate is being assessed on general flying ability possibly in a simulator type he has not flown before.. Support calls, particularly if the candidate is flying close to briefed tolerances, could be construed as a form of coaching. Coaching by the PNF is not permitted. This equally applies if the PNF is another pilot and not the testing officer.
Interestingly we had a case where the PNF would not shut up and was constantly "advising" the PF to the annoyance of the PF. It is a common habit with some pilots who mistakenly consider superfluous talking as evidence of good CRM. A more apt term is Fly by Mouth. The PNF held captain's rank which probably explained his propensity to micro-manage from the RH seat..