You are the one who keeps posting, "It doesn't belong! It doesn't belong!" So, simply as a mental exercise, just a bloody conjecture, how might have the writing staff of 1973 created an equivalent narrative, avoiding the legal hassles resulting from the Kzinti, ancient Slavers, stasis boxes, etc.
Sorry, I didn't mean that as a polemic. I was just talking about the ideas that come into play in the conversation. You mentioned "existing Trek lore," and I thought it was worth commenting on how the nature of what "Trek lore" is has evolved over the decades. I have a history degree, so I think of things in terms of their historical context. That's not about saying that X idea is right or wrong, it's just about considering all the historical factors that surround it. I think it's interesting to think about the evolution of how the Trek universe has been perceived and portrayed over the decades, and how different it was then than it is now. I think it's worth considering stories not just in terms of their in-universe content, but in terms of the real-world factors that shaped them.
Granted, I have a preference, but not in the negative sense you're suggesting. I'm not saying "It doesn't belong!" I'm saying it belongs perfectly -- in Known Space, a rich and important science fiction universe in its own right. Frankly I'm bewildered by people who say they like the Kzinti in TAS but have no interest in reading about the genuine article in the universe they were created for. I'm saying that if you like the Kzinti, you'll probably like them much better if you experience them in their home reality. Then it won't just be "The Slaver Weapon" with its skinny Kzinti in pink spacesuits; it'll be "The Warriors" and "The Soft Weapon" and the Ringworld
series and, if you like, a whole 13-volume, not-entirely-canonical Man-Kzin Wars
series by multiple authors. I mean, if you like Kzinti, you're really missing out by not reading Ringworld
and The Ringworld Engineers
. Speaker-to-Animals is a much more interesting and well-developed character than Chuft-Captain or Flyer or Telepath, and you learn much more about Kzinti culture through him. (Also, Nessus, the Pierson's Puppeteer in "The Soft Weapon" who was rewritten as Spock in "The Slaver Weapon," is a featured character in the Ringworld novels as well.)