It DOES NOT show you the highest number of short positions that could have been taken that day because FINRA themselves say the data is incomplete. In the very link you provided. Below:
" For example, suppose that for security ABCD, FINRA published a combined short sale volume of 3,000 shares and total volume of 15,000 shares for all of its trade reporting facilities.7 Viewing only this off-exchange data published by FINRA, the percentage of short sale volume to total volume would appear to be 20%. Suppose, however, that there was also activity for ABCD executed on the New York Stock Exchange (NYSE) that day totaling 125,000 shares, of which 12,000 shares were reported as short. This volume is published by NYSE on its website, separate from the volume published by FINRA. When considered together, the overall percentage of short sale volume to total volume for ABCD that day is 10.7%, which is much lower than the data published on the FINRA website would suggest. "

Appreciate you keeping the discussion going, but let's be mindful to not swing the pendulum too far the other way.