His "interpretation" or guess, wasn't worse or better than yours.

Therefore, his statement about a misleading title is not invalidated because you guessed in the opposite direction.

Let's say

Hypothesis 1

Article is negative (ChatGPT gave bad medical advice and that led to the E.R.)

Then * His guess -> is correct

* Your guess -> is wrong

Hypothesis 2

Article is positive

Then

* His guess -> is wrong

* Your guess -> is correct

Conclusion:

In any case you had NO way to know beforehand

So, in what ways pointing out that this is "his interpretation" invalidates anything he said?

Of course, it is his guess and based on the title alone, it's at least an equally valid guess as yours.

I say "at least", because it's not unreasonable to think that an LLM might have hallucinated some medical advice and that could lead someone to have an unhealthy practice which led them to the E.R.

It's the ordinary understanding of the idiom.