It's probably a political point, but I think your comparison over sells how inconvenient it is for someone to geoblock one small country and the headache if anything did happen. It's not much more effort than doing nothing really?
And clearly users in the UK can find their own way to read it if they like, so the cost is also small there.
Considering that there is multiple "why is this blocked in the uk" comments on every single one of these posts maybe the UK isn't such a small country. Geoblocking a decent chunk of your readership would be a pretty big inconvenience for a writer I would imagine.
the culture section of this writeup links to explicitly adult/erotic content in the footnotes and discusses 'adult themes' directly. his caution seems reasonable.
Have you even read the shit politicians are either pulling or trying to these days? There is no amount of paranoia that is too little when talking about things like cross national prosecution, laws regarding users not considered adults, and age verification.
He is either making a political point or excessively paranoid.