When we call createPendingThread in useExistingThreadInfoFinder, we need to include isViewer in order to make sure a PRIVATE thread is rendered as eg. "ashoat" instead of "just you". This is because the naming is based on ifJustViewer, which only applies if the members list only includes the viewer.
Depends on D13546
I don't think it is guaranteed that there will always be a response from the authoritative keyserver, e.g. when adding a new keyserver. We probably should add a condition here and extend a test plan to verify a non-auth keyserver auth.