I would be very curious to know what would be the results with a temperature closer to 1. I don't really understand why he did not test the effect of different temperature on his results.
Here, basically you would like the "best" or "most probable" answer. With 0.7 you ask the llm to be more creative, meaning randomly picking between more less probable moves. This temperature is even lower to what is commonly used for chat assistant (around 0.8).