Has there ever been any other recorded witness to this story? Obviously there was at least 3 other pilots and an air traffic controller, but I imagine there were more people on frequency at the time.
Additionally, can ATC equipment even depict that speed? For example, modern U.S. ATC equipment will not indicate the altitude of anything above FL600.
I remember there being a reddit comment that had quite a few upvotes debunking the story, but I can't remember what their reasons were.