Alright, is it possible you’re being a bit of a keyboard warrior here.
If an aircraft starts pitching down, and it wasn't commanded by the pilot, and resetting the trim (temporarily) fixes the problem, the issue is almost certainly with the trim. If it is MCAS and a malfunctioning sensor or a failing motor that occasionally kicks on and drives the trim to its limits, the pilot response should be the same. This is what I hear Walter saying, and it makes sense. MCAS just makes it more probable to manifest.
Hence, they might not have thought it was a trim runaway.