While you are correct, that's sort of irrelevant to the point I was trying to make.

I just don't understand the knee-jerk reaction that "so they are expected to have staff on standby everywhere?".

The regulation exists NOT as a blueprint for how an airline must structure their business so that they take all steps such that they never become liable for delay/cancellation compensation - it's there to spell out what is expected of them when their passengers are affected.

Staff members getting sick is not an exceptional occurrence - in most large organisations, you'll have numerous staff off sick every single working day. It's a part of doing business. The lesson is that it's not an excuse to deny compensation payments - not that they must roster extra staff on standby at every outstation.