Yes, I’m sure it was deliberate, intended as humor.
Captain Kirk Wields a Giant __nis - Star Trek: 2min
https://www.youtube.com/watch?v=ql8KzgSdgVM
As a kid, I didn't even think about it.
As an adult, I have no idea why it DIDN'T occur to me.
It is so obviously done.
I bet even Shatner thought it was pretty funny.
He HAD to be in on the joke or he wouldn't have done that scene.
I wonder if he's ever been asked about that.