It seems the pid.borg page is showing more signs of life than usual lately. Which is great, because let's face it, we know about 700% of what there even is to know about Marathon - but only about 100% of the story of PiD.
From facts & puzzling things about the epilogue, Jason Jones quote:
"the important thing about the hint book epilogue was to make all the player character's artifacts from the pyramid disappear from circulation before the marathon story begins."
Why was that important? What role would the artifacts have had in Marathon if they had been available to the player? In fact, does this confirm that the player is Eddings reanimated?