The comment is not at all just saying “their usage of their own AI is causing these issues”, it’s just a lot of hostility, I don’t see the value of these kind of insults.
Maybe it's just interpretation: "high on their own supply" is no different from "poisoned by their own dogfood" or similar.
It means that they have completely committed to a thing that the person proffering the quote thinks is "wrong" in some way.