As a biker myself, I can absolutely agree with the report on throttle direction.
During PPL training, I have turned it the wrong way for an auto (on instead of off), and on startup I have turned it off instead of on, more times than I considered reasonable for a simple error. The instinct on a bike is to roll it towards you for on, away from you for off. The more chopper hours you do, the less of an issue is because you think 'helicopter' not just 'hand on throttle', but after a history of doing it wrong several times, I now think positively about it every time I turn it. The bike instinct for this pilot was massive, mine was maybe 6 years?
I was concerned that I was getting it wrong during training, and just thought it was stress. It wasn't until I read the report above that I realised what the reason might have been.
In my opinion, the report is right to say what it does: there are a bunch of explanations for what happened, and some are compelling. But nobody will ever know. The family, who knew him best, will clearly feel that he was unlikely to make a one of the more serious errors laid out. Some pilots will feel that in stressful situations, that was exactly what happened. What is clear to me is that whatever happened he didn't intend it and it is unlikely that he did anything which he believed at the time to be significantly risky.
The best we can hope to do is take on board the possible scenarios and learn from them so that irrespective of whether they were or were not the cause of his accident, they don't become the cause of one of ours.
BW