It's fully based on the substance of the point as well. DHH's view is not just wrong, it's wilfully misleading, on a topic of enormous significance, to further a bad faith point. He could have retracted or amended it when presented with the facts; he has not. So this is a problem of substance as well as person.
From there yes, I get to a point about the person. IMO it is a useful practical definition of madness to pretend that someone acting in bad faith can be trusted to do it only on a single divisive topic.
Given two people, one a manipulative antivaxxer and one not: are you saying you don't factor your view on their anti-vaxx thoughts into their recommendations on other fact-based topics?
For me, these people simply get deleted from my brain, as far as possible.
These are simple judgements about the likelihood someone's opinion on a topic I do not know about is going to be good. When I know that their other opinions are clearly wrong and held in bad faith, I am going to take that into account.
(Where religion comes into things is where it becomes mostly a question of personality.)