It's really rude to ask someone about their medical conditions, even more so in public. Please don't do that. It is also not a good idea to attempt to diagnose

It's really rude to ask someone about their medical conditions, even more so in public. Please don't do that. It is also not a good idea to attempt to diagnose psychological issues from a distance. (But if we're playing that game, Wikipedia defines "autism" as "a developmental disorder characterized by troubles with social interaction and communication, and by restricted and repetitive behavior", and Knuth is supremely good at communication and remarkably good at social interaction for a (self-described) "geek" -- if you go over his life history (e.g. https://www.youtube.com/playlist?list=PLVV0r6CmEsFzeNLngr1JqyQki3wdoGrCn https://www.youtube.com/playlist?list=PLVV0r6CmEsFzeNLngr1Jq...) and consider all his activities -- being part of social clubs and fraternities, helping with the basketball team, dating and getting married, playing pranks on people, the affection with which he talks about his wife and children, his humorous outlook, etc -- then there does not seem to be any evidence of what you're thinking. Even the current article speaks of his warmth. But really, we shouldn't be doing this.)