The statement there is "perform as PiC of a multi-pilot aeroplane".
If a company's authority-approved procedures demand that an aeroplane is operated multi-pilot, then it's an interesting question whether it's a multi-pilot aeroplane or not for the purposes of an ATPL skill test, when the certification may not require it.
In the meantime, another interesting dichotomy is that for something like a Caravan, which is certified for single pilot operations as an aircraft, even if it's required to be operated multi pilot by company procedures, a CPL/IR holder does not require ATPL TK passes to gain a type rating and fly as F/O on such an aeroplane.
Would they need ATPL TK to fly as PiC? I assume so, as they'd need to pass the ATPL skill test to have a co-pilot. Probably. Maybe.
Mind you, that implies that
Captain Martin Crieff had passed the ATPL Skill Test, which is a little hard to believe, so maybe they don't.
G