QK exists mainly to protect Haqq commercial interests and shipping, so yeah. He probably doesn't like working with those guys but they're working towards a reasonable goal, rather than HB whose raison d'ĂȘtre is murdering people on the orders of a crazy hermit.
Are you sure, Sir, that this is a good place to write such controversial things? Maybe this crazy hermit knows your address? ;) :P PozdRawiam P.S. Gonna test Rahman in 200pts Holiday Tournament this Saturday in my Ramah Task Force.
If I remember correctly, he is a spacer himself, which in my mind would be his QK tie in. At the same time, Kaplans and Sekban are also fielded along side Yuan Yuans and Druze so I don't know that each individual must necessarily be "of the same alignment". As far as Hassassins go it just may be that he isn't one of the folks called upon to work with them. I believe Leilah was brought in specifically by the old man in the mountain and as a result is the only non-Hassassin character that they use.
Rouhani could also reasonably not be allowed on Hassassin operations cos he doesn't have clearance to join them. Not like you pick is it.
Tbh I think the reasoning was simply that HB still aren't supposed to get what amounts to basic infantry Core without limitations you'd care about. Lore reasons are something you can always make up later.