> they don't deserve the benefit of the doubt.
I really implore you to reconsider this position. Our world is wrapped up in injustice and political violence because everyone is jumping to extremist positions. And the last thing we need is declaring people guilty merely by association or poor attempts at empathy.
From a good faith reading of DHH's article, it's pretty clear he is expressing empathy for the feelings of the marchers (and even TR) without much care to the particulars (it doesn't sound like he himself marched or was personally witness to them). In the same way we allow for people to feel empathy for Luigi Mangione's motives without accusing them of also being homicidal.
You would be better off digging into DHH's actual problematic idea that he is trying to put forward: that the UK, or more specifically London, should fetishize and emulate the policy of anti-immigration countries. His actual thesis is bad enough and easily debunked without trying to pick apart "dog-whistles" and subtexts.
DHH is expressing a terrible idea, but in good faith. To maybe prove his point for him in an ironic way - Denmark can have actual harmful, racist, anti-immigrant legislation - but because no one cared about the rhetoric that was used they got it done.