Very interesting HG. I remember trying to buy when it was on the way back up and couldn't get any until it got around the .12 mark. Very likely some shorts did exit and some did just as you say. By looking at the volume that day should be a pretty good indicator how many shorts may yet remain. Hard to say how many closed out their position, but the volume should be a good starting point. No way can I buy the 1.5 billion number, but I do believe there is still a presence.
Another possibility HG is that the shorts were slowly accumlating a ton of shares prior to the big run on Black Friday to hedge their short positions and enable a less painful exit. These guys are not stupid as some here would like us to believe.