I dunno, @Zhampagne, if it's about keeping your hands busy the repetitive motion of darning might be calming, more so than swapping colours as you knit it up.
However it was done, he's clearly either charted the design himself, or adapted a design into a pattern. That aspect is something not everyone can do but the actual cardi itself wasn't complex knitting. Just stocking stitch.
I think he'll maybe do Strictly at some point, and he'll probably win that too.