Point taken - I was trying to point out that a description that is essentially Eaton advertising blurb may be overplaying the 'microprocessor' aspect of something that isn't quite so spangly. My guess (and that's all it is) is that you are correct and that the IGBTs are processor driven. I'd just suggest that the software is probably embedded and not particularly complex given the nature of that task so it may be doing digitally what was previously done by analogue means.
One of the reasons that seem to me to point away from the stab motor is that as far as I understand it the stab 'motor' did as we think it was told by MCAS (happy to be challenged on that)