Honestly, the islanders logic is dumb as fuck.
Just because one single outsider screwed them over once with a businesss deal that even they admit was "too good to be true", they go so far as to make a point of having no empathy for all outsiders in general. Despite that, the island seems to be state-of-the-art in technology, which would require outsiders coming and going quite often.
Also, they are in a fucking crisis consisting of giant insects trying to eat them! Shouldn't there be more important matters than some grudge?