Looks like the color is simply normalized so that one of the values is at maximum (255) and the others follow the shape of the spectrum. It's all very theoretical. If you're talking about what's physically possible, then you could just stop at "infinite temperature" instead of going into eye cones. Maybe if a body's temperature approaches infinity, you could get this color by standing at a sufficient distance, or wearing adequate sunglasses with uniform attenuation, or doing the correct safety squint like we do at the workshop.

See that's the problem. The author is using the "color our eyes would actually see" thing but only in arbitrary ways that generate pageviews. It's inconsistent and dishonest.