One of the challenges in interpreting TOS episodes is that many of us have read so much about them over the decades that our collective headcanon can crowd out what was actually onscreen.
It’s great that we can come together and make inferences, interpolations and extrapolations. Tie-in novel authors and magazines extend this further.
But the risk is that we come to a collective headcanon that can be quite rigid even though it’s certainly not the only way to look at what we’re shown and what’s said.
My recollection of my schoolchild’s reaction to the captain fighting the monster but choosing to be magnanimous and merciful in victory was that Kirk had burnt out his anger, and was ready to hold to his values.
More generally, I’ve been concerned for a long time that the message of the episode is so completely overshadowed by the cheeky meme of Kirk vs the guy in the rubber suit. Anything that can make the Gorn more believably terrifying to justify Kirk’s emotional response, and validate the significance of his choice to be merciful, is all to the good in my view.