Reading between the lines, Greenspun has presented these crashes as "the first mass killings by software". That claim looks clearer if you present it as wholly due to the absence of a few common-sense lines of code, and downplay the other systems design issues, such as the lack of triple redundancy, the failure to use the dual redundancy to detect sensor error, and the fact that the system was unnecessarily powerful, being able to drive the trim all the way forward.
At the altitude and airspeed at the time this last nose down was commanded, it can lead to only death, it's not recoverable, so yeah mass killing by software is not an extreme claim.
The problem is much more complicated than this and requires thinking end to end about 1) what the purpose of the system is, 2) when and how it should operating, 3) how much control it should have, 4) how it's activity is made visible to the pilot when it performs any control, 5) how and under what conditions it should automatically disable itself, or 6) be able to be manually disabled, and 7) how the pilot is made aware of all of these situations in a way that doesn't cause confusion in potentially complex scenarios involving other failures and alarms going off, and 8) proper training so the pilot can manage the plane when the characteristics have changed after the system is disabled. Oh, and 9) in this case since it's impossible for a pilot to manually trim a 737 when it's above a couple of hundred knots, making sure an electronic trim assistance function is available in this scenario (which it wasn't due to tragic idea to overload the use of the trim runaway cutout switches).
And I am probably missing a bunch of things, which is part of the point.
He's simply not solved the root problem and added a bad kludge for a single error case (AoA stuck > 25 degrees). While at the same time removed a potential safety control for a real world case where the AoA was validly over 25 degrees.
Note: I am assuming by RUNAWAY_TRIM() he means LET_MCAS_ADJUST_TRIM = TRUE; since runaway trim means something entirely different to my mind (that the electric trim is stuck/faulty and causing the trim to run to full deflection in one or other direction).