Surely this question hinges upon an interpretaton of 'requires' or 'required' ?
Who is doing the 'requiring' ? I think that it is, in the case of a non commercial flight - I have no knowledge of the rules governing commercials - in the remit of P1.
If two, both rated on type, are flying and one is designated P1 for the duration of the flight and P1 asks his - at that point passenger - to take over and fly the a/c that pilot (erstwhile passenger) without assuming command duties becomes the handling pilot and can log P.2. entering in the 'remarks' column; "Shared Duties".