I didn't say that AI images would or could be undetectable.

I pointed out that any software or program that detects AI images can be used as a training tool for AI image generation.

It is easier to use an AI detector that looks at file types or digital fingerprints to create training environments for AIs than it is to make AI detectors.

They still could be images with twelve fingers or nonsense writing, they just don't trip the AI detector software that was used for training.