Source: https://infosec.exchange/users/isotopp/statuses/115059833470035521
Transcript
Age Verification
Due to applicable UK laws, websites must verify the age of visitors using official ID to confirm they are at least 18 years old. We are a small site and unfortunately do not have the resources to implement such a system, so we are unable to serve users in the UK.
We are not required to verify your location, so please confirm below:
[I am not in the UK] [I am in the UK]
So extradition varies greatly. But generally (extremely generally, treaties vary a lot) countries will extradite if what the person is accused of is:
However basically no country will accept extraterritorial claims of another state simply because it impinges on their own sovereignty. It makes the UK somehow more soviergn than the country where the supposed crime was committed, in this case the US.
The exception to the above rule tends to be crimes against humanity and war crimes. But obviously that is irrelevant to this case.
You are correct that were they actual charged with a crime for violating this act they could not go to the UK.