Interesting announcement on social media rather than publishing somewhere like arXiv.

You can't please everyone on the internet, if he had posted this on Arxiv then someone else will be complaining that Arxiv is for humans to publish and that llm output should be social media post instead. Also, the proof fits in a tweet. So why blow it up.

a short counterexample makes it likely the best medium for such an announcement. would have been inappropriate for a positive proof.