the guy who attacked the little rock army recruiting station "was once detained in Yemen for possessing a fake Somali passport" [.] is there any other kind?
somalia hasn't have a functioning central government in almost two decades. presumably all the pre-1991 passports have expired. while there have been various "governments" that were recognized by some of the international community, those entities rarely controlled more than a couple of small patches of somali territory and were under almost constant attack by other factions. i would guess they were too busy with other stuff to issue passports.
if you're going to carry a fake passport, somali is the worst possible one to choose. it pretty much guarantees increase scrutiny. few border guards would have seen one before. plus the well-publicized lawlessness of the place would immediately raise questions about its legitimacy.