You are all seeing the limitations of Large Language Models (LLM), which is exactly that and understands absolutely nothing about the contents and its context. LLMs are great language tools, but only for those who see them as such and can identify and correct for knowledge domain issues.
Try telling an LLM its answers is wrong and give a hint as to what and see it oblige with perfectly good semantics, but no critical thinking abilities based on actual domain knowledge.
There are apparently two ways to categorize the 0.5 CDR-G result -- as either AD Stage 2 or Stage 3. The question then becomes, which way is the FDA using it for purposes of its draft guidance? Is the Agency using it in a way (as Stage 3) that would largely make its draft guidance ineffective for most clinical trials, or is the FDA using it (as Stage 2) in a way that preserves the utility of the CDR-G scale?