Kudos AvWeb for a well written, pertinent article.
This is definitely not the first instance where a demented (or malevolent) person tried to commit suicide while murdering lots of other people.
A good rule for Part 135 is ‘passengers ride in the back’. It wasn’t clear from the article whether that is SOP for this company, but the pilot always has the perogative to keep the right seat open.
The logistics of flagging questionable persons and making that information available to airlines or air taxi operations, sky diving, or any others who carry people not known by the operator/owner/pilot seem beyond do-able. We might as well just cancel flights for hire, charitable flights, or any other flight so unknown suicidal persons are denied access to controls, doors, etc.