We seem to have a fundamental disagreement with how guilt/responsibility is assigned. You seem comfortable that you know all the relevant details and applicable case law and that you can ipso facto assign guilt.
Wonderful for you. It would greatly simplify our legal system, think of the savings! We could all form a line outside your door and you could be emperor.
Wouldn't a more prudent choice (for you and PADI) to wait for those facts to be determined and then take action?
In some cases, enough facts are known right from the start. Remember that the case we are talking about is not a criminal trial to determine what happened. The case is a lawsuit to see what kind of compensation the family of the deceased will receive as a result of what happened. What happened is well known.
We have just learned in another thread to which I cannot link you because it is in a protected area that the basis for the expulsion was the incident report. The incident report is written by the instructor in his own words. Apparently there was enough there to let PADI determine that expulsion was called for.
We have also learned that after the incident report and expulsion, there was a police report. The police report was apparently much worse in its description of the instructor's activities.