Was confused myself as to why he doesn't do this. He mentions not having titles being an issue in Google Reader, but the same issue is apparent if you try to add the rss feed of his linkblog in Firefox; you just get a bunch of links with no details.
No, neither RSS nor Atom specify a maximum number of characters for TITLE elements. Which isn't to say that particular readers/clients don't truncate them, of course, just that the specs don't say they should.
Do RSS titles have character limits?