Really interesting article, following on from your discussion on the aesthetic and values of boxing in the Greco-Roman world, I think that the reason there is some overlap between how people in Antiquity thought about combat Sports and how Thais view Muay Thai might come down to the prevalence of Stoic philosophical values in the ancient world (particularly in Rome) which prized virtues such as self-control (temperantia). The idea of Stoic ethics often being to deny, remove, or overcome negative emotions (like fear, or anger) and impulses which they saw as illusory and due to misunderstanding or failing to anticipate a situation.
Stoic philosophers had lots to say about combat sports and often used it in analogies when describing philosophical concepts. I haven't done much research into this yet but this may have been because the nature of ancient Boxing or Pankration had coincidental overlap with Stoicism, perhaps Stoic philosophy and it's prevalence in the Ancient world had an influence on how combat sports were conducted, or even that because of the popularity of combat sports in Antiquity made them an easy subject to use when communicating complex ideas.
Here are some interesting links to some articles on Stoicism and ancient fighting. https://medium.com/the-stoic-within/simple-stoic-advice-61005b969540
https://medium.com/stoicism-philosophy-as-a-way-of-life/stoicism-as-a-martial-art-3ab9302071f9
https://medium.com/stoicism-philosophy-as-a-way-of-life/the-fighting-philosophy-of-cleanthes-of-assos-8a399416337d
https://modernstoicism.com/on-anger-and-impulse-control-in-boxing/