Worthy off mention, sure. But hardly a refutation of the WSI. I hadn't read about the classified parts before. Source?
It becomes even weaker without even a government spokesman summarizing its conclusions. In fact, they can't even find it:
Lewy said he does not recall if he saw a copy of the naval investigative report or was briefed on its contents. "I'm quite confident the information is authentic," he said. Paul O'Donnell, a spokesman for the Naval Criminal Investigative Service, said officials were searching for a copy of the report.
That's not correct; although Kerry wasn't happy when Hubbard's true record came out in April, 1971, he did not leave the VVAW until that fall. Neither was Hubbard removed -- he remained with the VVAW leadership into 1972.
Looking it up in "Home to War" by Nicosia...
Lawrence Spivak of "Meet the Press" found out "that Al Hubbard had lied about his rank, and probably about where he served as well" - calls Kerry right after the "Meet The Press" interview in April 1971. Kerry attacks Hubbard in front of the other VVAW leaders but argues for keeping him in, and defends him publicly.
Then in July something happens and Kerry attacks Hubbard again, and resigns from the executive committee. I don't know if this is when the DoD says Hubbard didn't even go to Vietnam.
I couldn't find out when Kerry left VVAW altogether.
The bullet point you object to doesn't claim to "refute" the WSI, it just notes what Lewy had to say about the report. That Lewy had access to classified materials is mentioned, among other places, in "Stolen Valor" on page 133:
"The results of this investigation, carried out by the Naval Investigative Service are interesting and revealing," said historian Guenter Lewy in his book America in Vietnam. His history of the war was one of the first to rely on previously classified documents in the National Archives. "Many of the veterans, although assured that they would not be questioned about atrocities they might have committed personally, refused to be interviewed. One of the active members of the VVAW told investigators that the leadership had directed the entire membership not to cooperate with military authorities."
One black Marine who testified at Winter Soldier did agree to talk with the investigators. Although he had claimed during the hearings that Vietnam was "one huge atrocity" and a "racist plot," he could provide no details of any actual crimes. Lewy said the question of atrocities had not occurred to the Marine until he left Vietnam. His testimony had been substantially "assisted" by a member of the Nation of Islam.
"But the most damaging finding consisted of the sworn statements of several veterans, corroborated by witnesses, that they had in fact not attended the hearing in Detroit," Lewy wrote. "One of them had never been to Detroit in his life." Fake "witnesses" had appropriated the names of real Vietnam veterans.
Lewy pointed out that incidents similar to those described at the Winter Soldier hearings did occur. "Yet these incidents either (as in the destruction of hamlets) did not violate the law of war or took place in breach of existing regulations," Lewy wrote. Those responsible were tried and punished.