All well and good, but assuming eyewitnesses said "they guy flew by at 80 mph", without knowing what caused the crash, we don't know if the crash would have been preventable had the driver been traveling at 60 mph. We can't assume that the guy wouldn't have crashed had he been driving slower. Maybe he was sending a text message, who knows?
I think spoon's point was not to detail the SOP for MVA investigation in his dept as much as it was to illustrate that eyewitness accounts are frequently incorrect, and that nobody admits to speeding when lying in the back of an ambulance. He's not suggesting "foul play" as much as factors that we cannot know....was there a mechanical issue, or some other factor like a sudden gust of wind? We just don't know.