I never met Brian but I have flown with former coworkers of his that have said nothing but the best. After almost 3000 hours in the MU2, mostly Marquis, I still have not lost the love for that airplane. Its a goofy beast but one you come to appreciate. I think it was the most demanding airplane I have flown to master.
I have mostly moved onto other things but I was out in the Mitz last night for a couple hours and I couldn't help but think of Brian.
Many have speculated regarding his slow airspeed....it may be no coincidence that 180kts is the top of the relight envelope. If he was having problems feathering a bad engine slowing down would have helped reduce the yaw or maybe something was wrong structurally like a loose tiptank many of these airplanes are very high time and have been ridden hard. This plane also has a history of throwing prop blades though none recently.
If Brian was your friend I am very sorry for your loss.
Fly safe y'all.