He doesn't get extra minus points for being rude about Norrell, if that's any consolation. Sylvia is perfectly aware that Norrell was hated by the fae. It's why they're so high up on the suspect list.

She chooses not to react to his remark about the situation being reversed. Honestly, they're not comparable situations. The Seelie and Unseelie are not people in the eyes of the law; they're creatures or even monsters in the eyes of some. The law doesn't recognise any justice system created by the Seelie or Unseelie Court, if such a thing exists, so of course she wouldn't hand any witch over to them.

But that's all hypothetical. She senses that the offer is the best she's going to get out of him, such as it is, and that will have to be enough. They'll continue the investigation without fae help and that is probably for the best.

She nods. "I appreciate the condolences. Well, I think we have said all that can be said. I'm glad that we were able to talk this through, thank you."

The 'thank you' is more of a goodbye, signalling the end of the conversation, but Sylvia is not unaware of the significance of having this communication channel with the fae. It's a tenuous and not exactly friendly link, but better than nothing.