The Austrailian government will be looking for husband's inconsistent statements. For instance, if the government has witnesses that say the husband was in a bear-hug with his wife, did the husband ever mention it himself when initially questioned or to anyone else? Problem is, he claimed he could not go after his wife because of an ear problem, he can't turn around and admit he was in a bear-hug with her. The obvious question would have been - why didn't he bring her up? Especially if he never mentioned the "bear-hug" to any others on the boat after the dive. I don't think he is going to admit to the bear-hug. If they have witnesses to the bear-hug, especially multiple witnesses and they are solid on the identification, the government could have an excellent case. The husband also said that the current took her away - it didn't, she was in plain sight in the photograph taken by a friend of a diver doing a safety stop, probably right near the boat. It looks apparent that dive master jumped in and had a bee-line right to her. That photo says a LOT!
I don't see he rescue standards as the meat of this case - it will be the husband's inconsistent statements. Trauma and panic is one thing, lying is another and it will be necessary to try and sort these out in a reasonable manner if the evidence is there. If it turns out the "bear-hug" witnesses are solid, his ommission and/or denial of being in a bear-hug with his wife - I would qualify as a lie, not traumatic panic. Stating that there was a current when there wasn't - that's a lie, not traumatic panic. Stating that he could no longer see her when she was in plain sight in good visibility, well, maybe. I've lost my buddy for short periods of time in good visibility, but usually not for long. I could see traumatic panic causing this kind of disorientation. For him to be innocent, you would have to say that he decided to make-up the current story to cover his guilt. In a trial however, jurors don't like liars and this will hurt him. I can see a prosecutor questioning him heavily on this point and about the photograph and asking him - why did he say that she was taken away by the current when it is clear she was in plain sight?