To be fair to the sponsors, I checked their sites first. I found many, many kilt hose. The difference was the elaborate patterns at the top of kilt hose, whereas those pictured had a simple vertical ribbing design. I don't think they're necessarily promoting them as something else, because they are not selling them - they supply them with a new kilt.

Most chunky knit socks I found were either too short, or like thermal hiking/explorer socks, not knitted wool-rich blend.

I shall search some more...