They most definitely have a melee specialist and most definitely are not raiders nor supremacists.
On a side note, I need a dedicated sheriff/judge/executioner/etc specialist. Basically a law enforcer. Is there a chance it could be added to the base game or should I just start modding already?
I have some experience modding Skyrim and checked out basic Rimworld modding tutorials. It doesn't look like adding a new kind of specialist is an easy task. Have anyone tried it yet? Modifying a meme (to allow melee specialists to all Buddhists for example) is a trivial XML edit though.
For law enforcement you just need someone with good social and good melee that can arrest people easily without incident. A dedicated role isn't needed, since once you have maxed out your arrest chance you only lose by having a dedicated role for law-enforcer since those deactivate some other jobs.
Yep, and for the melee specialist just use Ducks' No Limits - Ideologies.