Just played through Crookspur Island, though not meticulously.
Near as I can tell, all four factions (sorta) want something to do with the slavers.
VTC: Want to make a deal so they can get funding (?) for ships.
RDC: Want to wipe out the slavers
so they can build a military base there for the Good of Eora.
One Principi leader wants to wipe them out, another make a deal with them so they can then make that side-deal with the VTC mentioned above.
The Huana is the only one that seems to be left out, but you they're interested through the Wahaki clan (who understandably want the slavers pulverized).
Now if one just goes in and smacks Master Kua around the head and then leaves, it can mess things up a bit. HOWEVER, if you make sure to free both sets of slaves in the dungeon, then Aedyls will be very happy with you that you freed one set of slaves (as opposed to slightly happy if you just kill Kua) and Furrante will say the equivalent of "whatever".
More to the point if you tell the VLC that those slaves deserved to be free, they'll swallow their complaints and you'll still get a very minor rep boost with them as well.
The RDC is, of course, delighted. As for the Huana, I don't think they give any direct bennies, but whacking the slavers and freeing the other set of slaves is an easy way to get on the good side of the Wahaki clan, which is important to the Huana.
In fact, near as I can tell the only people who will be upset if you go in and lay waste to Crooksupr, is, well, the Crookspur slavers.
And to that I have to say: Suck Flavers.
I think the key reason everyone is happy (more or less) is that these slavers are enslaving people they aren't supposed to (Deadfire residents). The Watcher confirming this AND freeing the slaves puts the VTC in a bit of a bind, as they can't be TOO upset with you, otherwise people would start asking questions they'd rather not be asked. So they'll make a show of patting you on the back and say "Good job, ol' sport" but pretty much half-heartedly and then turn around and hope everyone forgets all about this without asking too many questions.
The Principi as a whole, as opposed to certain individuals, is rabidly anti-slaver so naturally Aedyls singing your praises will give you a boost with them as well.
Edited by Zap Gun For Hire, 07 June 2018 - 08:06 PM.