Bitmex is a hyper speculative platform built on a simple principle: short positions are less risky than long positions. If you calculate your liquidation price, for the same amount, entry price same, same leverage but fid different positions being short will give you more space for price action upward. Your risk will be lower and so, under high uncertainty being short results less risky. If we think that on Bitmex we can always exit at anytime and enter at anytime this makes of Bitmex the real Demand/Supply BTC market. A 190 million Dollar liquidated in a few hours is definitely influential on the BTC price action. Bitmex shorts have dumped the market plenty of times and those are not use cases, real world application, just speculation where being bear is less risky.