aircraft which have an air data computer (that interprets raw data and process it in some way before displaying it as flight parameters) will automatically display CAS on the PFD rather than IAS. I.e. the computers do the calculation from IAS to CAS. So basically that speed we're looking at is CAS not IAS .
I would think of it like this: in this case the IAS
is CAS. The instrument and pitot static error have been removed, the total system error is 0 (within some tolerance), and CAS = IAS.