I suspect their reasoning was: It only trims down by 0.6°, what does it matter if a faulty sensor accdentally activates it. The plane is still flyable slightly

I suspect their reasoning was: It only trims down by 0.6°, what does it matter if a faulty sensor accdentally activates it. The plane is still flyable slightly out of trim and the pilots can easily correct it. The 0.6° number was what they said immediately after the Lion Air crash. But their reasoning was wrong. Turns out, MCAS was actually adjusting trim down by more like 1.5° and they never considered that a faulty sensor would trigger multiple MCAS activations and move the stablizer all the way to the end of it's range.