He responds to a thoughtful and detailed 600-word comment from a maintainer with a dismissive "Here's the AI-written copyright analysis..." + thousands of words of slop.

The effort asymmetry is what's rude. The maintainers take their project very seriously (as they should) and are generous enough with their time to invite contribution from outsiders. Showing up and dropping 13k lines of code, posting comments copy+pasted from a chat window, and insisting that your contribution is trustworthy not because you thought it through but because you fed it through a few LLMs shows that you don't respect the maintainers' time. In other words: you are being rude. They would have to put in more upfront effort to review your contribution than you put in to create it! Then they have to maintain it in perpetuity.