andrewr I think you need to to read up on how TCAS works. The only thing that is accurate about TCAS is the altitude. Both bearing and distance are best guess worked out by an algorithm using a few assumptions on the signal strength.
Actually that is my point. The report relies heavily (exclusively?) on the TCAS data. As far as I can tell it is only the TCAS data that indicates that the "near collision" even happened - there is no visual confirmation mentioned in the report.
If you think incorrect TCAS data is more likely than a GA-8 doing 200 knots and overtaking a jet, it also seems likely that there was no near collision.
If you use more likely speeds for the GA-8, it was probably never closer than a mile to the jet, with the gap increasing.