It either is unconstitutional or it isn't. Morrison is vote driven. At the moment the focus is on the states and not on the sport rorting feds.
As to your response, it doesn't matter about mistakes and problems in other states. If a Premier chooses to close borders it is up to him. It would obviously be in his interests to have them open as soon as possible if it was safe. I'd say West Australians are pretty happy with the WA premier's actions so far. I see SA has just announced a couple of infections btw.
It seems that Premiers around the country being very cautious has paid off in spades. Even in Victoria ironically.
Andrews was criticised for keeping the initial lockdown going for longer than everyone else so that he could get the testing regime in place. Morrison initially had a dig at him over it and then backed off. Now it seems just as well Andrews was so cautious given the hotel quarantine fiasco that was bubbling away under detected. Fortunately it has been largely contained in Victoria rather than being replicated across the country.
Having a border closed is inconvenient but it isn't anywhere as inconvenient as having Covid wafting around the state.
