A common truth is that for every population, there exists a sub group of that population whose IQ falls well below the mean average.
In other words, they're stupid.
The name of the Archon of this Kabal translates roughly to "keister", a name given to him by being the lowest kabal of the the dark city in size, influence, guile or tact.
Keister's kabal homes the discarded morosis of the dark city. His warriors are alive because it wasn't worth the effort to kill what amounts to Aeldari simpletons. And that's just fine, as they are also not quick enough to understand what that means.
In much the same way as Ork's seem to have an innate affinity for crude technology, the workshops of Keister house outcast Aeldari savant's, unable to understand metaphore, but miraculously able to craft great weaponry (coughobsidianrosecough).
Keister allies himself with disgraced Wych cult exiles, some of which who band together into tiny "Biker Groves", uninterested in fighting and who accidentally cause misery and suffering by lack of wit and clumsiness than anything Machiavellian. Their motto "Gotta go fast", is about the only thing they can conceive of.
If anyone in the dark city bothered to watch Kieisters Kabal, or the Wyche Exiles he bands about with, they would realise part of Keister's continued existence is owed to an unrequited protection effort made by a deep and obscure Haemonculus Coven, who for no other reason than interest occasionally send a detachment of Wracks out raiding with the Kabal to report back why the kabal continues to survive, despite their stupidity.
Subject: Keister's Kabal 
Tue May 01 2018, 21:58
I do feel sorry for those poor Kabalites
