If you define feeding of copyrighted material into a non-human learning machine as theft, then sure. Anything that mitigates legal consequences will be a fig leaf.

The question is "should we define it as such?"

The fact that they have guardrails to try and prevent it means OpenAI themselves thinks it is at least shady or outright illegal in someway. Otherwise why bother?

If a graphics design company was using human artists to do the same thing that OpenAI is, they'd be sued out of existence.

But because a computer, and not a human does it, they get to launder their responsibility.