I'd think that it's commonsense that 44 degrees is rather hot and is extreme by most measures.
I suspect that, if asked, the tennis players themselves would be more than happy to have the roof closed and the air-conditioning turned on. Whilst it might help their opponent, it would also help them too. And I'd think that those sitting there watching them play would also be glad to not be passing out etc.
I see it as an issue of safety. You have a major sporting event open for the public to come and watch. A very large number of specators and some players have had medical issues due to the heat. To me, that's more than sufficient evidence that they ought to do something to avoid this problem. And since they have a roof and a means of cooling the place already there, it seems crazy to not be using them.
Anyway, off the subject of tennis it seems that the power supply has coped with the heatwave. It came very close to blackouts on Wednesday but, with the exception of a few isolated transmission problems cutting off individual towns etc, the system as a whole worked better than anyone really expected it to on Thursday and Friday.
It seems that the trains in Melbourne had a lot of problems however, at least they did judging by media reports. Without being too critical, I really don't see why they can't get them to run reliably. Trains aren't exactly a new technology, and the need for expansion joints has been understood for a very long time.
Fires - It's mostly cloudy but what sun there is has turned orange in Hobart at the moment. Not sure where the smoke is coming from, but something's obviously on fire.