flybymike: It certainly seems ironic that a qualified and current pilot may fly as a passenger with a medically restricted one and be expected to save the day if the other collapses at the wheel, but yet the same pilot may not fly with another who is fit and well just in case they both crash and perish because one of them has only done two landings in the last 90 days (maybe even both of them yesterday)
The role of safety pilot is completely different, don't introduce more confusion. The safety pilot is just that...a safety pilot, a required member of the crew and is not a passenger. They can log it as SNY.
MJ: I wasn't suggesting it's law, just providing a reference to answer backpackers question.
I think the answer to the OP is that the law isn't 100% clear. The problem will only occur if you have an accident!