Personally I think red flags should be reserved for serious incidents where a driver needs medical assistance or clean up/barrier repair is likely to take more than 15 minutes.
None of the incidents in Australia came close to meeting that requirement.
And red flags should be restarted as a rolling start, not standing start. Standing starts makes it seem like a 2nd race, rather than a resumption.
I think even under VSC or SC, there should be a new flag that is waved 1 timing point before and after the incident zone and in that zone the pit lane speed limiter should be engaged (to prevent the fact that currently under SC or VSC cars can be moving very quickly between time points as the system currently measures time delta, not top speed).
That would make it ok for the circuit to be "live' despite work going on. If this is not ok, then surely a pit lane is not ok either...