I agree that we frequently see this on HN in regards to aviation. However, I don;t think it applies to Greenspun. He's a knowledgeable and active pilot himself.
That still doesn't mean he knows anything about writing code for flight control systems in commercial environments. Maybe he's written some toy code in MATLAB demonstrating some things, that's never undergone testing on a real airframe.
Its quite likely he has greater knowledge of both subjects than the person who physically implemented MCAS.
Sadly, no speculation is necessary. Had that change been included in MCAS the Ethiopian crash wouldn't have happened.
"all of the problems on the Ethiopian flight could potentially have been avoided by changing....about 10 characters of code"
It's a sign that things are never as simple as they seem on the surface.