Yeah, I don't think redundancy would have prevented this. What could prevent this is stuff like canaries. Or automatic rollbacks for this kind of change, with the change having to be submitted in two steps, one where it is applied, and one where it is manually confirmed that the change worked (or automatically by a system outside the network). If no confirmation is given after a certain time, the system should revert to the old configuration.
Of course, we can't really know for sure until/if they release exactly what caused this issue.
