I take this to mean that if the nodes are disconnected from each other, Synctus disallows all access to certain files on node A; i.e. the files that node B currently owns.
Yes, that's right. Although currently it provides read-only access if a replica (not necessarily known to be the latest) is available, so I suppose that's not quite fully C in the read-only case. In the future, this might be a configurable option.
Do I understand correctly?