Missionaries bring aid because they bring the Gospel. They wouldn't bring aid without bringing the Gospel. But like that idiot who tried to convert the Sentinelese, they would bring the Gospel without aid, if they felt so compelled. I don't think it's incorrect to say that everything else is a means to the common end. Christianity is an assimilationist religion. Jesuits may do it differently than Catholics who may do it differently than Baptists, but conversion is always the end goal.
>You've also underestimated the agency of indigenous cultures and their ability to appropriate Christianity, so much so that some Tiwi Islanders (islands to the south of PNG) insist that they converted the Catholic church when it embraced them.
I mean, they didn't, that isn't ever really how that works. Whatever Catholicism they appropriated will inevitably erase and obscure their culture and identity, as will the influence of Western culture. I couldn't read the article you posted unfortunately but I did find an article that basically seems to tell the story[0]. I also found an article written by someone of Tiwi descent that tells a less friendly, or at least more complicated story[1].
I'm more willing to believe the word of a native over a Christian missionary, all else being equal. It may not be fair but history demonstrates that the relationship between Christianity and indigenous peoples is one of exploitation, suffering and colonization more often than not.
[0]https://www.abc.net.au/religion/tiwi-christianity-aboriginal...
[1]https://www.thenorthernmyth.com/2017/12/20/graverobbers-god-...