Why do you think it was ludicurous? Admittedly I don't remember any detailed account of these events - but as I understand it Wright demonstrated that he can construct a message with Satoshi private keys. Most probably he used some trick there, a rigged laptop or maybe even rigged internet connection. But it was quite reasonable proof for me - I would not expect someone to do tricks on me when he could not demonstrate the same thing publicly - because what would be the goal of that? And if you are so sure that you could not be tricked - then good luck.