Interesting, I can think of a few possible examples of where this may be used in some form.
1. The bbc is funded by a licence fee, so they block content in some countries
2. I have seen adverts on TV ( I live in England) for say legal services, within the message at the bottom of the screen it may say something like 'not available in Northern Ireland as I think the laws are different. So said company could block internet users in Northern Ireland from viewing that content.
But yes, this idea is a good one to protect companies from legal action for non GDPR compliance or perhaps other laws.