I am thinking that there could be two types of short sellers...

I am thinking that there could be two types of short sellers potentially involved here. Each different in their wants and needs. There could be shorters with no opposing open long which as a trading vehicle is generally closed out quickly – seconds, minutes, hours, days, and then also those shorters acting on a pure long hedge who can sit idle for weeks. If you are correct I would find it more likely that those with no hedge are closing out if they have determined an increase in risk - for what ever reason, especially if margin loans are involved. My opinion only of course!