I have been reading up on distant islands for years. The topic is fascinating and seemingly endless (wikipedia now has more and more articles covering these remote specs).

However, Tristan da Cunha was uninhabited and the current settlement is part of the modern world--just significantly limited by distance and difficulty of access. It is fascinating to study how humans live and relate in such small communities, but Tristan's inhabitants are fundamentally unlike the Sentinelese with their status as an uncontacted tribe.

The difference being, people can and do go to Tristan da Cunha. I know someone who's been there. They have telephones, internet access, satellite TV and a radio station.