I think HDR is a feature of UHD, but just because HDR is being brought in doesn't make him right. Especially when he was talking specifically about UHD Bluray disc-support from what I gathered in his thread.
HDR is not a feature of UHD, you can have UHD without HDR (lots of TV's are like this), and you can theoretically have HDR without UHD as well, though I'm not sure if any manufacturers have made screens that are 1080p and HDR yet (or ever for that matter), but still, HDR is not a feature of UHD.
He was not right. This is ridiculous