Nowhere in the article does it mention these are specifically for "premium" economy, these seats are, according to the article, supposedly meant for your run-of-the-mill economy cabin.
CNN got this wrong, and the rest of the major press is citing CNN as the source.
But if you look, you can see that these seats are clearly not economy seats -- they're too wide, and they have all the premium economy trappings (doubled armrests, drink tables, etc.)
Don't blame me ;) Perhaps the user I replied to should have provided citations. I suspect you're not wrong, but neither of those two sources I'd recognise as "notable".
As much as I enjoy being a part of these sorts of conversations, I don't sit down with the intention of writing a dissertation whenever I disseminate information.
Anyway, those two blogs the parent posted are pretty well known and respected in the avgeek community.