Comic Strips

Carnap’s statement is false, humans find all sorts of non-verifiable beliefs and experiences cognitively meaningful.

I think Carnap's conception of "meaningful" differs from the "cognitively meaningful" term you use here. Which from context, I gather means something like "personally fulfilling" or "socially important". Carnap along with the other logical positivists were trying to develop a philosophy of science that didn't depend on metaphysical claims and was ultimately grounded in empiricism. Carnap's use of the term "meaningful" is more akin to saying that a concept can be connected to the empirical world. Meaningless claims, then are the opposite, they cannot be connected to the empirical world.

Imagine for example that you and a friend were the victims of an attempted mugging turned violent, but to you and the mugger's surprise you discovered that you were impervious to attacks with lead pipes and laser guns. As you are searching for an explanation for these newfound powers your friend suggests that the reason you have these powers is that you both, without your knowledge, are wearing magical rings that give you super powers, but the rings are invisible and cannot be felt by the wearers. Carnap would say that is meaningless because the ring explanation cannot be connected to the empirical world. The explanation requires an imperceptible entity.

Trying to draw a bright line between empiricism and metaphysics is not scientism, in the pejorative sense that you mean here. I think to qualify as such Carnap would need to dismiss all meaningless (in Carnap's sense of the term) propositions as totally lacking in personal value. I don't know his writing well enough to say whether or not he holds that view, ( a brief reading of his entry in the Stanford encyclopedia of philosophy suggests, no he did not hold those views) but I don't think that conclusion is a particularly charitable reading of Carnap's criticisms of metaphysics.