I think you guys should open a new thread discussing legal, insurance issues and regulatory issues .
As far as Aviation professionals are concerned this is a clear case of a pilot having accepted to do a flight for which he was unqualified. Period. The rest is for the lawyers..and whether it was private or commercial ops is for the judge to determine in the end..
Can we prevent this from happening again . No. There are always 1% of people that want to bend the rules. Tightening the rules will not change that , just affect the 99% of us that do follow the rules...