If you read carefully, you see that the North Vietnamese General doesnt say a person is responsible, but a set of strategies and actions caused us to lose - he does say bombing the North would have been effective, bombing the HoChiMinh trail wasnt, the antiwar movement was an enormous help to them, and the VietCong were an integrated part of an explicit war strategy directed by the North Vietnam Communist Government, and they were aided more by the Soviets than China. Bombing the North, cutting off supplies and training South Vietnam would have been a successful US strategy.
You are correct that LBJ should take the blame for having a failed approach to the war, because he failed to do any of the things the North Vietnamese General says would have worked - LBJ & Co. were too incremental, trying to defeat a symptom (the VietCong) and not the source of the aggression (north vietnam), and not having a clear vision for success, and interfering too much in military decisions.
The Communists in Vietnam had a plan since 1961 to take over the whole country through aggression, though, and even JFK gets some blame for worsening certain things. Nixon's policies and the fact that Tet was in fact a US military success (though we didnt know it at the time) might have turned the tide sooner, but as the general noted, we withdrew forces under Nixon. But Nixon eventually came close enough to the successful formula in 1973 with Linebacker bombings that he acheived the Paris Peace Talks and won the same kind of peace treaty achieved in Korea in 1953. A ratified stalemate.
It could have remained at that stalemate post 1973, but antiwar activism and sentiment left America unwilling to do even minimal effective things to save South Vietnam. Watergate made it worse. Our will had been sapped. On that latter point IMHO some blame does rest on anti-war activists like Fonda, Kerry and others for doing their part at sapping our will. B-52 bombing runs in February 1975 would have ended the North Vietnamese invasion in its tracks as they had 100,000 armored troops in concentrated formations highly vulnerable to such couterattack. But we didnt lift a finger in 1975. If we bombed them, they would have withdrawn as the General points out, and South Vietnam would have been spared the horrors of the re-education camps, boat people, etc.
On Kerry
"Blaming Kerry is to blame me." You dont need to attack the strawman. I said repeatedly this is not blaming Kerry for 'Vietnam', just for his own actions and their consequences - you share that blame only if you engaged in the same actions. What Kerry did wrong was tells lies to Congress that defamed the military... I blamed Kerry *only* for this - reposting my comment: In 1971, John Kerry became a leader of the Vietnam Veterans Against the War protest group. Kerry testified to Congress that American soldiers in Vietnam had "personally raped, cut off ears, cut off heads, taped wires from portable telephones to human genitals and turned up the power, cut off limbs, blown up bodies, randomly shot at civilians, razed villages, shot cattle and dogs for fun, poisoned food stocks, and generally ravaged the countryside of South Vietnam." Kerry testified, "We all did it."
He said his claims were "not isolated incidents but crimes committed on a day-to-day basis with the full awareness of officers at all levels of command." The awful allegations of fellow veterans being war criminals were based on trumped up stories. B.G. Burkett points out in his book "Stolen Valor" that Kerry used phony veterans to testify to atrocities they could not possibly have committed. Kerry had engaged in defamation and slander against the military in order to further the anti-war cause.
And I also said this: Kerry is responsible for his words. He lied. Why cant we hold a man responsible for submitting testimony that is based on false and phony allegations? Why cant we point out that he smeared the military? The lies and distortions of the "Winter Soldier" agit-prop 'investigation' and the inflammatory nature of his testimony to Congress are in the public record.
Unless you were a part of the "winter Soldier" agitprop brigade, unless you also testified falsely to Congress, you cannot share the blame for his slanders.