Not as much as you'd like to think of the "western world" is northern and western Europe. The "rest" of it includes, among other things, most of eastern Europe and pretty much all of South America.

The "western world" as a term is understood to mean Australia, Canada, Catholic and Protestant Europe, New Zealand, plus the United States [definition from wikipedia]. Not saying that isn't silly, but everyone understands that the western world does not include those other places.

It's a rhetorical bait-and-switch. It is "understood" to mean (essentially) Protestant Europe when making strong claims, but gesturing at the broader notion of West to imply a scale larger than that at which the claim is credible. In any case, even "Australia, Canada, Catholic and Protestant Europe, New Zealand, plus the United States" is too broad of a definition to make GP's claim true.

You'd be more right, and also it'd sound notably less impressive than the expansive claim about the western world.