I personally think the gladiator like raiders would suit a lot better to an EA version of this nation which would probably be filled with stealthy cavalry and recruitable djinns. Sadly if I ever want to make the same loosely arabic theme for an another era, it'll most definately be LA.
I was thinking of a loosely Ottoman empire based highly bureucratic one where magic is highly institutionalized and an underground Abdul Alhazred cult with something like fire/death/blood/astral-mages (probably really low level and/or random paths though) along with the official state sanctioned fire/water scholarly ones. Fire because I want to give some era a possibility to actually summon ghul (edit: actually an ifrit bey with a death random can do it) and the idea of corrupted/dead/whatever djinns sounds kind of cool too. If djinns are beings of smokeless fire, they could be beings of smokeless banefire ;P
I think two riders on a dromedar would not work without making that basket, and I believe the camel riders just simply are cooler this way. I personally like my mods as streamlined and smooth as possible and somewhat detest having multiple units on the same sprite. Technically I could make camel archers summon a foot archer unit for every battle, but that kind of feels like a non-smooth hack solution too.
Also, for me historicity doesn't really matter much as Dominions isn't a very historical game. Personally I think al-Nadim is quite historical enough when compared to other human nations in the game. It feels arabic to me atleast and that's enough for me
EDIT: Oh yeah, regarding militia. I reckon I'll make a leather armored version of the spear infantry next time I can be arsed to. That should serve as a weak but not as terrible militia unit.
Also, I did just realize that the shortbow archers aren't there just for the theme. There's plenty of fire to access flaming arrows and that should warrant archers in some cases.