I agree with him that you can endorse someone's work without necessarily endorsing their personality. An artist is not their art, a programmer is not their code.
That's not the point. It's not a simple split between what someone does and their personality. Especially with art, personality is also often expressed in what you're doing.
But it's more the case that people can do both good and bad things. Good people don't do good things ALL the time, obviously. So it makes sense that one can appreciate and value the good things being done, while condemning the bad things.
And maybe help the other person to correct their faults.
The problem with "cancel culture" is all there. The purpose is to identify and isolate the bad apples, with little space left for correction. In this same thread I've seen a few calling that dev a fascist, maybe because it makes him easier to hate.
People saying stupid, bigoted thing should be called out, loud and clear, but the intention should be correction. And a community should be inclusive, not in the sense that it tolerates the bad, but so it does all it's possible to recuperate the bad apples. As long the other side is open for a civil discussion, which is not always the case.
Same as the above, "cancel culture" can be both good and bad. There are truly nasty aspects to it, same as there are important parts that cannot be brushed away.
(and it's the very opposite of "being in the middle". It's about doing precise judgements, and avoid to succumb to the simple "average". It's the longer, more complex path.)