This citation admits that it's pure conjecture how many North Sentinelese died due to outside diseases. Neighboring tribes on neighboring islands suffered heav

This citation admits that it's pure conjecture how many North Sentinelese died due to outside diseases. Neighboring tribes on neighboring islands suffered heavy losses, but you specifically claimed that large numbers of natives of North Sentinel Island died. As far as I can tell, it's highly speculative third-order conjecture that (1) large numbers of them died due to diseases acquired through contact (2) they have a belief that quarantine will protect them (likely despite not having a germ theory of disease) and (3) this is their reasoning for killing outsiders. Medieval Europe was significantly more advanced, and they had all kinds of strange ideas about the cause of diseases and plagues that prevented them from mounting effective quarantines. We can't expect them to have the same feelings we do about killing outsiders, and I think it's a stretch to project our understanding and values on them and then to back out a reasonable Western-style justification for their actions. I think it's much better to admit that we know very little about their system of moral reasoning and give them the benefit of the doubt that their killing of outsiders under the specific circumstances they found themselves in is moral within their moral framework.