I suspect how accurate his measurement is depends on how consistent the surfaces are.
When I measured the course in Peoria in 2008, there were hard spots and soft spots and tall grass and grass worn away, etc. And that was using the first 300 meters of the race course as a calibration course. It's very difficult to calibrate on the same surface you measure on.
I suspect his method is more accurate than using a measuring wheel, though, and to insist on the use of a steel tape would be foregoing good in pursuit of perfect. Or something like that.