Well, no, that's not what he'd want. What determines a faction's special units is in crusaders_unit_prod11, but it's kinda at the begining of the line, right before the long bit about types of units there is a "Ruler ID troop advantage" and right after that is "Region ID troop advantage" that says for like Highland Clansmen "Scotland" or most of the time is gives a faction name (or "NO_FACTION" or "ALL_FACTIONS" if such is the case). This is not the only faction that can build a unit, that's later at the end of the line, so there's a second "Scotland in the line that is the one that limits it to the Scotland province. If you make the Swiss playable, you'll have an advantage for training pikemen.

But generally, unplayable factions aren't given too many of these, cause, well, you wouldn't normally care. But you could go down and split up some of the perfered factions. The Golden Horde does have "GoldenHordeHorseArchers" and "GoldenHordeHeavyCavalry." However, the sicilians don't seem to have anything, Venice does produce Galley's faster so if they had Venice, they could do that.

Patrick