The version of "meat proxy" I've heard is the person who forwards a machine-answer to someone else who didn't ask for a machine answer, and could just as easily made one themselves.

Calling someone a "meat proxy" for being the human in the loop is wild.

I don't think that's quite the problem the OP is pointing out. A corollary of "meat proxy" is "cognitive surrender." [1] In both cases, blindly pasting AI output and being an "Enter key presser", you have surrendered your cognition. In the latter case, you're in the loop but there's not a lot of reason for you to be.

Your underlying supposition is right, though. If you are truly thinking and in the loop, you are by definition not a meat proxy. I think those are the people who are successful with AI coding tools, but it takes discipline and it's still hard to find the joy and reward when you're not the one solving the problems.

[1] https://swiftrocks.com/using-ai-without-losing-critical-thin...

I think it might be appropriate if what we're talking about is a human connecting an LLM to something it can't natively access. Like something in the physical world - a piece of hardware, a different human, software the LLM can't access. As the human in the loop your role might be to mostly just shuffle information back and forth from this external resource. But depending on the situation there could still be quite a lot of interpretation and analysis performed by the human in the loop.