The requirement for operational airpseeds in the AFM is 'indicated':
(c) The units used in the Airplane Flight Manual must be the same as those marked on the appropriate instruments and placards.
(d) All Airplane Flight Manual operational airspeeds, unless otherwise specified, must be presented as indicated airspeeds.
Yes, I agree, noting that this requirement is for a latest FAR Par 23 certified plane, but is not a requirement for a CAR 3 or older 23.1581. CAR 3.777 makes no mention of IAS/CAS. CAR 3.778(a) also makes no mention, though points you to 3.757, which refers to TAS (just add to the confusion, I suppose!). 23.1581 does not seem to mention IAS until revision 23-50 of 1996. So any plane certified prior to that would not have to comply.
So the complication comes in a later manufactured CAR 3 plane (like a 172/182/206) where the requirement in the certification basis (CAR 3, and earlier 23.1581), did not specify presentation in IAS/CAS, so it's not required, but Cessna presents it anyway, as they would be required to for a latest 23-1581 cert basis plane. Using the C 206H as an example, its a FAR 23, amendment 6 cert basis plane, so it's not required to comply with 23.1581 at amendment 50, but Cessna can voluntarily do so, and it's wise. I find that generally, Cessna go the extra distance for POH information (probably at the legal team's advice!)
These details are well beyond what we would expect the pilot to be aware of, and it's probably annoyingly confusing to most pilots. But, as the planes and certification basis have evolved, and flight manuals/POHs have been refined, pilots need to be reminded to read and interpret what's presented in the POH in context. IAS/CAS awareness is important if you're actually using an airspeed indicator during flight near the stall speed. It's extra important if you're setting up and AoA system, and then has an additional layer of complexity for each lift mod installed on the plane.