Yes, I'm aware that the Dead Rats are behind Gothwan's disappearance, and no, I definitely don't think that it's a coincidence. Of course they're after the Crown. But they're also our allies, as much as a gang of criminals can be our allies. Moving against them openly would do us far more harm than good. Not only would we lose their assistance in our smuggling operations, but fighting the Dead Rats would leave us open to Neverember's thugs. So, you see our problem.
We'd be fools to expect that the Dead Rats had anything but their own ends in mind when they offered to ally with us, but sadly, there are more important things at stake here than Gothwan's life. When the Nashers take the throne of Neverwinter, we will have our revenge. But for today at least, we must let the Rats live.