Don't conflate "hacker spirit" with "unethical spirit".
Someone with gumption might just go ahead and use GPT to train a model and then open it up as a paid competitor. Poking the bear is certainly an interesting way to spend a year for the adventurous.
If I were the author I'd never do this because I would want an exit and this strategy + twitter thread wildly complicates any potential exit.
Even though I don't think there is anything particularly morally problematic here (I'm an information freedom maximalist).