The article was almost right until here but this is just unbased. The truth is: The Byzantine Empire fell in 1204 and then Tyrian purple fell into disuse. The late new Byzantine Empire under the Palailogos had already switched to red and gold as their royal colors, and the Palailogos-Ottoman transition didn’t change this.
https://exhibitions.kelsey.lsa.umich.edu/ancient-color/index...