The issue makes sense Tim.
The current ajax module should throw an exception on network failure and this is passed to "notification.exception" to show an error dialog.
I imagine a lot of different use cases for what to do when the network is down. Moodle is generally written as a series of individual pages, not as a "single page" app that never refreshes and just calls webservices. The exceptional cases on that tracker issue are the rare cases when there is something to do on a single page without reloading or saving that might take an extremely long time.