The article is missing some critical details. What does the fund do? The article suggests they do arbitrage. Those opportunities actually tend to increase when things are volatile. Also while you can lose money doing it you wouldn't expect a precipitous collapse in NAV. If you discover you're slower than everyone else you can shut down. Volumes aren't necessarily correlated to price either, so that isn't entirely con…
My guess is that his fund got locked into a levered position on one of the exchanges like BitMex for trying to trade too much then couldn't get out for 24 hours. This kind of thing is more common than you might expect. There are also very few exchanges that allow margin trading, leverage or shorting, and all the ones that do have, uh, questionable compliance practices.