You completely missed this point. To quote the article:
> Many people, especially those in marginalized groups do feel less welcome. We know because they tell us.
Hanlon doesn't claim to know why the marginalized groups feel unwelcome. He doesn't even claim that the root cause is a bias of action -- conscious or subconscious -- on the part of SO's users or staff. What he said was these groups report at a higher than average rate the feeling of being unwelcome. That is a simple fact, and can only be dismissed at the cost of saying those people's opinions are not worth addressing. Acknowledging it, saying "maybe if we get creative we can improve it", is not virtue signaling, it's the most fundamental requirement to:
> shift from “don’t be an asshole” to “be welcoming.”