As PF (and Captain): at the 100KT call by the PM, I look at my PFD for my IAS as per the SOP. This is where the training / published guidance / procedure ends on the Airbus...hence my pre-plan for this event (if my IAS is not at 100 knots) is I will glance to check the IAS on the standby/ISIS and then the GS readout on the ND and make the appropriate decision based on the circumstance at that instant. But in my mind it’s not a blanket reject, nor is it published procedure / guidance to do so.
I’ve given this very scenario some thought when I first moved to the left seat, for the very reason that there is nothing published telling us to reject if there is a discrepancy.