If he was flying 'their' plane, ie the private company it was not a public transport flight as the passengers weren't paying a fee for their seat.
As for the type rating, it depends what he was flying.....I haven't read the report but I am guessing you are refering to the Seneca accident. You will find that the pilot may well have had a 'Multi Engine - Piston Land' rating which allows you to fly any piston twin under a certain weight, can't remember off hand what it is, but the Seneca certainly falls into that category. Normally the owner (usually a school, club etc) would require you to do a few hours under instruction to familiarise yourself with the a/c, but I think I am right in saying that for a non public transport flight there is no legal requirement for this.
As I have said, I have not read the report.....just answered what you posted, so I don't know how relevant it is in this case.
PP