Yes, the quote that the cover makes use of is actually Kerry repeating the accusations (of atrocities in Vietnam) others had made; he is not making the accusations based on his own eyewitness experience. Nevertheless, he was presenting these accusations to Congress, and not in the context of refuting them. This isn't some sort of movie-review trick where the reviewer said "This is not a great movie!" and the studio clipped ". . . great movie!" for their publicity. Kerry was, in fact, retailing these accusations, and a certain responsibility falls on him not to repeat accusations he can't verify, particularly before Congress. TNR is trying to let Kerry off by the same technicality that Howard Dean appealed to when he talked up an "interesting theory" that Bush knew of 9/11 in advance.
Beyond that, we're talking about the cover, for god's sake. No doubt the editors at TNR are up late nights fretting over how the New York Post, Newsday, and the Daily News use incomplete quotes and wordplay to make a flashy headline page.
Finally, we're talking about opinion journalism. Tell you what, I'll hold my breath until TNR spanks the Nation, too. Look closely at that cover. Did Bush really say that? Think it? Tsk, tsk. Fret not, TNR will have the cover police over there on the double.