By your criterion, what Samuel Slater did was also immoral. Yet I'd argue it was actually for the common good. There's an argument to be made that most IP law itself is immoral as it grants monopoly rights whereas in most other context we recognize monopolies as naturally immoral. In fact, it goes against a very natural inclination to share interesting knowledge and stories.

IP law is an attempt to recognize that there's some value in granting limited term immoral monopolistic rights because it net produces a better result longer term. That doesn't mean that IP law itself doesn't open up an immoral land grab and is itself open to abuse. Similarly, we obviously recognize that the commitments themselves may be immoral & thus can be broken (e.g. marriage to an unfaithful spouse) or licenses with immoral clauses should be free to be broken (e.g. you can't sell yourself into bondage).

That's not to say that your experience isn't one where the other player was immoral. I'm just trying to broaden the horizon of the discussion beyond your personal story to how we should think about IP more broadly. It's nowhere near as clear cut as you make it and that illusion stems from how the Western legal and education systems work (which is a whole other topic - passing off another's work in education is "plagiarism" whereas if you do it literature it's "ghost writing").