safetypee But even after they got into "MCAS difficulties" they seem to have retained a reasonable degree of control initially. It wasn't a case of "the MCAS thing happened and there was immediate loss of control". More "the MCAS thing happened, some time passed while the crew maintained a degree of control but were unable to resolve the problem, then (possibly due to a change in circumstances) they then lost control". The initally part of 672(b) usually addresses things like using the flight controls to initially counter an AP runaway, long enough to hit a disconnect of some kind. It's usually only a period of seconds.
With 20/20 hindsight, they had control long enough to have disabled the stab system had they decided to so - so I would expect that aspect of 672(b) to be passed. That text is really there to require an AUTOMATIC corrective measure of some kind if the crew can't at least initially maintain control. I would not say such was needed here.