Zapp - if you're not current to do the flight, you're right - you cant log as PIC, but you also cant log it as ICUS. If your currency has expired, it has to be dual - no other option.
So if you're out of 90-day currency (IFR currency, not just single-pilot currency), you can't simply go up with a (non-instructor) rated+current+endorsed safety pilot as your PIC? I haven't come across this yet, so haven't thought lots about it apart from a quick discussion as mentioned.