Did you look at the spreadsheet he linked to in the footnote where he calculates the cumulative effect of surge pricing? Where would you like to quibble with the math?
https://docs.google.com/spreadsheets/d/1N4NiwuPLo78w9PaoqXRa...
https://docs.google.com/spreadsheets/d/1N4NiwuPLo78w9PaoqXRa...
I think I mostly find it incorrect to essentially take a pin-hole view at the data through 5-6 averages, and extrapolate it towards a somewhat biased result.
As for the other data they describe their collection methodologies, and the numbers they produce are in line with trends that Uber has indicated. You're certainly free to produce a dataset of your own but until you do that this one doesn't seem especially bad or anything.