SMN is one of the 4 pet jobs we can use in FFXI, alongside BST, DRG and PUP. However, SE didn't decide to add SMN to the Shepherd's Chain neck item dropped From Okyupete: http://wiki.ffxiclopedia.org/wiki/Shepherd%27s_Chain
It should be on there for 2 reasons:
1) As stated above, SMN is a PET JOB.
2) Misareaux Coast AND Okyupete were released in the CoP expansion, which came out a year and a half after RoTZ for JP PS2 players.
Please consider the above and add SMN to Shepherd's Chain. Even other non pet jobs can use this, so I don't see why SMN can't.