I'll say up front that I'm never a fan of the trope wherein a villain has the protagonists captured and leaves them alive without a clear justification. I'm not saying there is no justification, either, but it wasn't made apparent through the writing. Based on what I do know, I'd assume that Laermont's team is too large to easily cover up making them 'disappear.' He needs Laermont's cooperation as well, because even if he makes individual deals with each member for their silence, only one needs to break the alibi, but they'll likely follow Laermont's lead if he makes a deal.
So on a meta level, I can presume to know why they're alive. I would have liked to see some of that going through Laermont's thoughts, to better justify his assertiveness. If I'm correct, it's not an assured victory, but Mercuti and Laermont both have assets and risks. Just the fact that Mercuti ends with "we're at an impasse" is a victory for Laermont, since he's the one in bondage.
I'm rather curious to see where the story with the Others is going. There's not much else to say on this chapter alone.