I think the point you are missing is that nobody is challenging that the conductors on the PV side of the disconnecting means are in fact feeder conductors... or better yet, non-service supply conductors. The question you asked of the NFPA did not distinguish concern solely for the conductors on the service side of the disconnecting means. Maybe to you it did, but I don't read it that way, and I don't believe the NFPA representative did either. The reply you received only addressed your query from the standpoint of "supply" conductors. Conductors on both sides of the disconnecting means are "supply" conductors... and the response addressed the PV supply conductors but did not offer a precise point of demarcation.. which is what we want. You assume the reply says the tap point rather than at the disconnecting means... but I don't see it that way.
The question posed was specifically about the conductors between the PV disconnect and the POCC. The person at NFPA was quite aware of this the his answer related just to those conductors. The conductors on the PV system side of the disconnect are not part of the question or answer.