Even if their conclusion is OK, the reasoning "'Xi' was not used because it is a common last name" is based on a lie. 'Xi' is not a common last name. It happens to be the last name of the largest dictator on this planet, but it does not make it a common last name.
Xi is absolutely a common last name. What are you on about? Just checked the white pages for Xi for San Antonio because I used to live there and there's pages upon pages of results. Same for every other bigger US city I've checked.
