Racial tensions are always good. And Tzvi, at least, is used to it. 

Going off the top of my head, Errol could be a Shadow Broker lackey or doing a freelance job in cooperation with Zhar (Shadow Broker agent), or as an extra layer of security/snooping for said Shadow Broker. Particularly if Errol seemed more disposable and thus a good investment to do the riskier things (although Zhar is resourceful and does things well on his own). Or he could be working for a small-time, rival information broker.

He could be the employee/lackey of most the guys there, similar to Mark, since he's a mercenary doing a variety of odd jobs. I'm not sure how hard it would be for him to be in Quantum (Mosis?), but that's one possibility if it's not too exclusive, high-class, or high-rank for Errol.

He could be there to steal some nice tech?? :P For himself or someone else.

I've got a couple basic ideas if the mission Derv and I whipped up is the next (if you want to do the next-quest shiz), but there's no guarantee what mission will come after the last.