The ECU most definitely does use the AFM at WOT. Believe me, I know from my experiences designing & tuning my MAF conversion! If you have the settings wrong and the ECU sees a bad air flow signal, you will run super rich or lean at WOT, which would not happen if it was ignoring that input. It uses both the AFM and IAT signals at WOT. If it was just using throttle position and RPM to look up fuel table bins, it would be more of an Alpha-N setup, which it is not.
You are correct that it ignores the NBO2 input, though. As far as I can tell, the ECU goes so far as to turn off the O2 Heater Relay when you are at WOT or over 4000RPM. This was the death of many WBO2 sensors (with my LC-1 setup) until I realized this and jumped the relay pins so that the O2 system always has power as long as the fuel pump is running.