To be clear I don't have a beef with the author of the article, but the missionaries themselves. I just thought it was odd to write an article about foreigners going up into the PNG highlands and not mention missionaries at all.

Not sure whether it's intentional in the context, but interesting Freudian slip type use of the word "crusade", you might want to consider its etymology and origins.

Very much intentional, because just like the crusades, you're fighting against some imaginary enemy in a very misplaced location. The article is about different set of foreigners going to the highlands, the first ones, which weren't missionaries, so of course the article doesn't talk about the missionaries...