This is my question: why just one AoA sensor? It seems like there is plenty of space on the nose to put two or even four. Their results could be averaged. Presumably the MTBF for any individual AoA sensor is quite low (if we're happy to fly planes with just one right now), so this shouldn't cause too much of an increase in maintenance burden.

I don't actually know how many AoA sensors there are, but the NYTimes article seems to refer to refer to them in the singular when talking about this plane.