These are very experienced Travel Counselors, so I asked them if they think I could fly AAA-PVG (stopover)-NRT (transit)-AAA visa free. Their immediate response was that I cannot as this would abuse the TWOV rules. I don't know who is right here, but if Travel Counselors who mostly deal with complicated, international itineraries think something is wrong here, I am quite sure AA agents can be even more confused...
Their opinion might be that you are abusing the TWOV rules, but this doesn't reflect the operation of TWOV.
There is lots of speculation as to the definition of 'transit', or 'destination', or whether a ticket is returning to where you started. Perhaps because of all these complications and definitions Chinese immigration take a very simplistic approach. They don't look at anything beyond your immediate 'in and out'. Makes it very simple for them. And very simple for us.