While this is a decent article to stimulate thought, it has too many details to be taken totally seriously. There is a significant vibe of : "Do it like me, or else you are a fraud."
My personal view (as a computer scientist) is that you shouldn't call yourself a "user experience" designer unless you have a background in cognitive psychology. Otherwise you're simply a designer.
Abdulla, does HCI count?
Sure. HCI encompasses, and is heavily motivated by, cognitive psychology.
Many of those would apply to product management as well.