The people quoted in the article are all fairly well known in the field, and while I obviously can't speak for them (especially because each of them alone has much more experience in the field than I do) I expect that they generally have realistic rather than what I might call sensationalistic views of this result. I expect this is also true of the authors of the work in question, though of course they may be even more excited about the result (with good reason). To be clear, this is an interesting result, and is certainly food for thought, but I think it's too soon to tell how much of the "cuprate problem" it solves.

I my guess that the sensationalism in the article is just a combination of overexcitement and misinterpretation by the journalist. I think most people in the field would agree that this result is interesting, and could end up being quite important. If the journalist heard something like this from everyone he asked, he may have misinterpreted this as the matter being "settled" in the view of most of the community.