There is no outstanding news explaining that extreme rise of shorts. I would say, it is likely the Occam's razor rule case: bears were in loss and were waiting for the certain level of bitcoin when the correction (global falling trend) is expected to step in again.
And don't forget that all those shorts are basically sell orders and even such a huge selling pressure didn't lead to a price drop, it means that there was many buyers, which were merely balanced by shorts (we can see it by the volume without a big price change).
Eventually though those shorts might serve a nice fuel to make the price rocketing if such process will be initiated.
Not a financial advice.
And don't forget that all those shorts are basically sell orders and even such a huge selling pressure didn't lead to a price drop, it means that there was many buyers, which were merely balanced by shorts (we can see it by the volume without a big price change).
Eventually though those shorts might serve a nice fuel to make the price rocketing if such process will be initiated.
Not a financial advice.