/u/qwerqmaster on reddit:
According to the Guinness World Record's article[1] the
cube has to follow the World Cube Association's
regulations[2] on competition legal cubes. The WCA allows
modified/custom made cubes as long as they meet a list of
guidelines, which this modified cube does.
[2] https://www.worldcubeassociation.org/regulations/#article-3-...