I think it was both of them trying to be tough guys and not let on how incredibly beat up they were but also showing some respect to the other. I felt like Kong standing up but putting the axe down was him kinda saying we’re cool and we don’t need to fight anymore but if you want to fight again I’ll scrape til I drop. Neither of them were in any shape to fight again and I doubt Kong had anything left in the tank to dodge Godzilla’s atomic breathe like before. Even though Kong probably wouldn’t have lasted much longer, he was never going to submit.
Yeah the plot was stupid (something about energy?!?) and Godzilla being able to just blast a hole to hollow earth when they had made a big point about the challenges of getting there was incredibly silly, but it’s still a fun movie that knows exactly what it is. It’s not trying to be super pretentious and have some hidden deeper meaning. We just need a paper thin plot to get us to the point where these two iconic monsters beat the hell out of each other.
I was thinking about how it seemed like a happy ending but I found it a bit depressing. now that humans can access hollow earth, it’s just a matter of time before they destroy it. They’re probably going to extract all the energy and natural resources and start putting up condos. Humans finding new land rarely ends up well for the natural inhabitants.