Did you read the explanation? Every trade, except those where the MM/broker happens to have an exact matching buy and sell offer in house, is technically a short because they first sell the shares on order from your Broker after which they buy the shares from the Broker that they just sold on his behalf. it could not be done any other way.
This is a perfect example of a bureaucracy giving us volumes of information which is technically correct, but absolutely worthless. I would much rather have a daily report which shows the short interest, if any, still existing at the end of the session.
"Libenter homines id quod volunt credunt"