I dont know how the C5 thrust levers are, but in every jet I've flown, when you secure an engine you move the lever to "cutoff" (below the detent). This way, it doesn't line up with the other levers at flight idle. Seems like a different procedure could have prevented this accident (along with going out and running some proper checklists and then commencing the approach)
Very unfortunate accident, and very preventable.