I don't think that matters here, though I agree with what you said. There's also going to be redundancy on the other mechanisms that can lead to runaway trim, b

I don't think that matters here, though I agree with what you said. There's also going to be redundancy on the other mechanisms that can lead to runaway trim, because runaway trim can be catastrophic, because we don't assume that pilots are perfect, and because (as you say) runaway trim can happen in situations where the ground will necessarily arrive before your recovery does. I think it takes around thirty seconds for the trim motor to move you from one end (where both crashed planes had it) of the jackscrew to the other. And that's with the motor! If you cut out the motor because it was literally trying to kill you -- and as Boeing advises you to -- you'll have to use the hand crank and it will take much longer. Runaway trim at low altitude is death. It really seems to me that the MAX as shipped was not plausibly airworthy (due to the use of a single sensor). I think even Boeing's going to agree eventually.