It amuses me a little that the header for the piece describes Mr. Watterson as "reclusive." As far as I can tell, that word gets applied to a lot of writers, especially those who aren't anxious to have a lot of press or public interaction, as if the desire to get out there and live fame to the fullest were normal and anything lesser were therefore suspect.
Maybe he's just an introvert. A lot of writers are, after all--writing means spending quite a lot of time in your own head. I go crazy without sufficient time in mine.