The data from FINRA is accurate as stated...the number stated is the total registered shorts since Aug 2009....I don't believe that the post mentioned that this is what's out there currently as a total...and only stated that every day since that point has short shares being posted...
However in my opinion it is difficult to cover shorts whem ACCUM trends on the chart are heading north..more ACCUM usually means there isn't much selling so covering becomes much more difficult...
Usually a squeeze occurs betweem 85-90% of the float being shorted due to the fact that the MM's will get a letter from our friends at the S E C once they get closer to 100% of the float