Not only was Jobim a much better pianist than guitarist, but he resented being presented as a guitarist, which was largely due to Sinatra's insistence (the TV special, the album, etc.). He felt it perpetuated the image of the "latin lover with the guitar." He played guitar only because everyone in Brasil played guitar. But piano was his true instrument (aside from the pen).
Larry, you really should read Ruy Castro's "Bossa Nova" book if you haven't already.