If stocks hit $0, you probably have more immediate concerns - like where you are going to get your next meal and if someone is going to shoot you for the contents of your fridge.
Stocks could still continue to fall, but they aren't going to slide to zero.
When faced with "cash in hand that might lose value through inflation" versus "the stocks you currently own at risk of being worthless", the decision to sell is straightforward even in the absense of a next step.
There is always a risk that a specific stock will go to 0. It happens even in good ecconomic times.
The decision to sell is not straightforward, even given the current situation. It would probably be the wrong decision for the average person unless you really know what you are doing.
> Brazilian hyperinflation lasted from 1985 (the year when the military dictatorship ended) to 1994, with prices rising by 184,901,570,954.39% (or 1.849×1011 percent; equivalent to a tenfold increase on average a year)
If I had the same $1000 in stock, and it lost 11% of its value in 2 days, I might worry about it being worth close to $0 by the end of the month.