This is overly simplistic and, pretty damningly given the topic, fails to account for the market drop between Feb 20 and Mar 20.
When the traditional investors (as opposed to the automatic ones) sold in volume?
I think this is a great point. Retirement dollars come in a steady stream and but a consistent bid in the market. If that money flow stops, what are the implications for that buying impact. You could dig further and look at unemployments rise and see whether those who have lost their jobs typically save for retirement.
If CoViD had put white-collar people out of work, there wouldn't be any buyers and things would tank.