To be clear I'm not saying that Pike's response is appropriate in a professional setting.

"This project does not accept fully generated contributions, so this contribution is not respecting the contribution rules and is rejected." would be.

That's pretty much the maintainer's initial reaction, and I think it is sufficient.

What I'm getting at is that it shouldn't be expected from the maintainer to have to persuade anyone. Neither the offender nor the onlookers.

Rejecting code generated under these conditions might be a bad choice, but it is their choice. They make the rules for the software they maintain. We are not entitled to an explanation and much less justification, lest we reframe the rule violation in the terms of the abuser.