The author claims: chatGPT has a 1400 chess ELO based on games played.
You appear to think author claims: chatGPT plays chess like a human rated 1400.
Your observations do not contradict the authors’ claim that based on games won and lost against opponents of a specific strength, the estimated ELO is 1400.
A non-human player can make illegal moves at a much higher rate and make up for that by being stronger when it does not make illegal moves to achieve the same rating as a human player who plays the game in a completely different way.
The author claims: chatGPT has a 1400 chess ELO based on games played.
You appear to think author claims: chatGPT plays chess like a human rated 1400.
Your observations do not contradict the authors’ claim that based on games won and lost against opponents of a specific strength, the estimated ELO is 1400.
A non-human player can make illegal moves at a much higher rate and make up for that by being stronger when it does not make illegal moves to achieve the same rating as a human player who plays the game in a completely different way.