The point is that while Watson is a big step forward in language processing and information retrieval, it's unfair to conclude that he does these things as well

The point is that while Watson is a big step forward in language processing and information retrieval, it's unfair to conclude that he does these things as well as the best humans. Jeopardy isn't a particularly good test of these abilities (though it is good theater) because the additional variable of buzzer-timing screws up your results. As was pointed out by another commenter, if the game had been "everyone who knows the answer write it down and get credit", Watson probably wouldn't have won, and absolutely not by so much. So I think Jennings is just cautioning us not to assume that AI has achieved human level language and information capabilities when really a totally unrelated and unimpressive other dimension of the game is the culprit.