In the context of CJ's original post, I suspect this is tangential, though as above I'm not entirely sure... infanticide, superstition, or some combination thereof might be the mysterious X. (Or, rather, their negation might be.)

If X is anti-infanticide, I think the original claim is simply wrong, but I do agree that real people do propose bringing X to cultures that lack it (as you describe with the Banna). And there's probably someone somewhere objecting to that as cultural imperialism, though probably not with much support.

If X is anti-superstition, the original claim might be right and is worth experimenting with, and I'd grant that people like Hitchens and Dennett and Dawkins could be construed as proposing bringing X to cultures that lack it, including my own. (And they are definitely objected to as an analog to cultural imperialists.)