What does Australia care? They're going to feed him for 11 months and then kick him out of the country for good. Why should they pay to fix what will apparently be the US's problem? Even if they appeal the sentence, what is the most severe thing they can do to him at this point? Do they throw out the plea, or give him the max sentence for what he pled to?
Also, I was dismayed when the judge referred to Tina's "deregulator" in the sentencing comments. It would seem that maybe he knows nothing of diving and is therefore in under-qualified to judge the likelihood of Watson's panic defense.
What does Australia care? Enough to try to do justice for all involved rather than allow a trial by media and pressure from people whose decisions are based primarily on emotion to pressure the Judicial System into compromising it's purpose. A case based on Circumstantial evidence in Australia is probably viewed differently than in the USA.
Judges make decisions based on law with access to experts where needed/appropriate on technical matters. If it were otherwise no decisions could be made ... how could a Judge decide if someone was really dead/cause of death unless they did the post mortum themselves?