I added a tiny little 2-input OR gate to pins 9 and 10 of the 24-pin LD-V1000/PR-7820/PR-8210A connector. These pins (unless I am greatly mistaken) are only used by the PR-8210A. One of them is the remote control signal from the game hardware and the other indicates whether the remote control signal should be heeded (ie not ignored).
In addition to improving performance so that the AVR doesn't have to think about this logic, it also avoids using an extra pin on the AVR (which is pretty much full as it is).
The OR gate essentially turns pins 9 and 10 into a single pin that is only low (active) when the game hardware is really trying to send a command to the player. And the thing is so tiny (2mm) that one could sneeze and never find it again if one isn't careful.