I did read it over again.
You're making an assumption on how to read it, another assumption would be that Alisaie is horrified because she is worried about the other assistant.
Sinis may be stuttering because he failed to mention losing contact with his brother. As to not to worry Alisaie.

It's small, but it's a mistake that could be fixed easily by either adding something like:
"Alisaie's Assistant: But I'm-! U-Upon that note, my lady, there is something I must tell you. I am sorry to report that I lost contact with my brother just over a bell ago..."

Or just making the names correct.