> the probability of the detection tools flagging completely human generated text as AI generated is non-trivial
How does that follow? AI-generated text is already not a perfect emulation of human writing. There's lots of room to affect it laterally without changing the level of quality.
As I understand it, LLMs with temperature >0 can select from many possible outputs. All they're doing is limiting the possible outputs to ones that contain this pattern. I don't see any reason why the quality of that subset should be lower than average. The very best outputs will likely be eliminated, but so will the very worst.
To sample from the probability distribution you already need random numbers.
If you get your random numbers from a cryptographic PRNG, then to notice the difference between that and 'real' random numbers even in theory, means you need to break the cryptography. In practice, your gut feeling about how good some text is won't break modern cryptography.