Framer, by my arithmetic, the flight had an ETA of 44 min before last light. So by your guidelines there would have been no concern about conducting it as a VFR flight.
Karom has introduced so many red herrings its hard to deal with them all. But there is no suggestion (other than yours) that Thunderstorms, icing, mechanical failure, or aircraft performance had any role in the accident. Its debatable whether or night darkness (possibly ahead of declared last light) had anything to do with the accident.
I don't know where the insurance argument has come from either. I don't think there is any suggestion that the insurance cover for the passengers would be any worse than a commercial operation. Indeed their situation may be significantly better than if there was a $2 Pty Ltd holding company behind an AOC.
And what with the final quip about tax deductions? Tax deductions don't have anything to do with this. None of the pilots, or ground crew gain any tax benefit whatsoever. I'm not even sure that Angel Flight has DGR status. In fact it costs me quite a bit to do Angel Flights.
Finally, there was another really tragic accident last night by one of the best equipped operators with a highly skilled professional pilot. All of those who have criticised the Angel Flight operation would do well to reflect that similar accidents can happen to the best pilots, with the best training.