I couldn't find anything about VPNs in the link you shared.
If that is the case, I disagree with it. But if you serve the UK market, you gotta follow UK law. That doesn't seem unreasonable, does it?
I see you removed the VPN reference in your edit and it made your argument quite a bit weaker imo.
Just because 4Chan is in the US, doesn't mean they don't send their data to the UK.
As soon as they do, they are subject to UK law. Quite simple. If they don't want to be, they can stop sending their data there. See also the magic mushroom parallel from earlier.
> So tell me, how can one exist today and not "operate" in every country where internet exists
You could IP block by geo for example? Seems pretty straightforward.