This site was better with him on it. So what if he said a lot of crazy things? If you let a crazy guy offend you, I think that's a "you problem." He did not have the position or power to act on his prejudices; he wasn't hurting anybody in any real way. Posting here obviously meant something to him, since he kept coming back and creating new accounts. It was cruel to shut him out.
Propagation of harmful sentiments from anyone, but especially someone who (rightfully) inspires admiration will spread those further to people who are easily influenced or unable to separate a technical brilliance from someones capabilities in the rest of their life.
To be clear - Terry remains an inspiration to me, but I can understand the predicament of a moderator who needs to maintain a space.
People aware of Terry's condition might be willing to put up with his antics, but that's a minority. Everyone else just sees this crazy stuff being posted.