I'm kind of torn on this, because on the one side I can see the developer's troubles. If they have 30 years of experience and they considered the impact of using it they will most likely know how to use it properly and ethically. Indeed many of the issues people have with AI are a kind of redirected anger, when really they are issues with capitalism, incompetency, or digital illiteracy. And the person posting the issue seems purely there to fan that flame rather than actually contribute. Something maintainers could use just as little as slop authored PRs.
But on the other hand, being open about the usage is a must. It's the price to pay for going against the grain. If your ideals and means are pure, they should be defendable and scrutinizable to reasonable people, and there should be no issue with that in the long term. Hiding the usage will create doubt about authorship, and make defenses harder to point at, while it won't stop the horde.
Avatar really is a case study in mismanagement. At it's core an engaging story with deep characters and lore with many parts unexplored, with a special place in many hearts after the initial series. The perfect ingredients to turn into a lifelong franchise. Yet it cannot seem to shed the curse of rights holders and suits smothering it's potential success.