I think you're not too far off.
Here is an excerpt from The Fifty Year Mission (book 2) by Mark A. Altman and Edward Gross. I highly recommend those books. They are super insightful about the behind-the-scenes stuff from the first 50 years of Star Trek.
However what I don't think is justified is the label as one of the worst Star Trek episodes. Is it nuts? Yes. Is it annoying that they have the technology to bring everyone back to Earth and simply de-lizard them after the trip, and then it's never brought up again? Also yes.
But it's nowhere near the worst episodes because it's neither offending and un-Star Trek (like TNG's Code of Honor) nor is it boring. It's actually pretty entertaining for the first 35 or so minutes. It just goes off the rails at the end.