Why not simply estimate it yourself? These sorts of things aren't very hard to do. For example, you can estimate typing as follows: peak at 120 WPM; words are average 4 characters; each character (per Shannon and other's research; see http://www.gwern.net/Notes#efficient-natural-language ) conveys ~1 bit; hence your typing bandwidth is 120 4 1 = <480 bits per minute or <8 bits per second.
Do that for a few modalities like speech, and sum.
I've just noticed he said “an arbitrarily fast mind running in a human body”, not an actual human being, so I don't think it would be much slower at typing uuencoded compressed stuff than natural language (at least with QWERTY -- it might be different with keyboards layouts optimized from natural language such as Dvorak, but still probably within a factor of a few).
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.