Earlier quoted context omitted.
Unless they IP ban the whole of the EU, they will still be subject to the GDPR once any EU citizen accesses their site. (Which, agreeing with AmericanChopper, is a purely theoretical thing - until the moment where YC wants to conduct any kind of business in the EU)
Simply being accessible from the EU does not automatically mean the GDPR applies to a site. See Recital 23: https://gdpr-info.eu/recitals/no-23/
Ah, that's a fair point, I didn't see that.