The AI doing the programming was trained using theft. If theft of intellectual property is wrong, as he says it is of his output, then it’s wrong for training programming too.
“I don't like their policy, but I accept it as it is because it is not possible right now for me to paint on something else.”
To give a comparable example, I hate proprietary software, but I still run some of it on my computer, because avoiding all proprietary software everywhere is extremely impractical in current day and age. You can take a meaningful stance against something without being Stallman levels of principled.