I read the DHH post in question: https://world.hey.com/dhh/as-i-remember-london-e7d38e64. It is pretty standard anti-immigrant. It feels like it is acknowledging the fact that the populations of Western countries are in a demographic crisis, they are sub-replacement in terms of fertility but instead of fixing that he just wants to ban immigrants. It feels like fixing the fertility issue would solve the root issue.

You don't need to carry water for racists and invent more palatable explanations for what they said. There's nothing in there about not enough British people - only about too many foreigners (whom he can tell by looking at them).

That is always the case with this kind of rant. People want to have the cake and eat it too.