True. The Japanese wouldn't win against the US in a prolonged conflict. But the operative word is "prolonged."

IN Guadalcanal, during the beginning of the campaign, the Marines lacked supplies, didn't have a complete defensive perimeter, and did not enjoy air superiority. At one point of the campaign, the Japanese succeeded in destroying the entire aviation fuel supply of the Cactus Air Force. I don't think these are conditions that assure the US a won battle. That's why I don't consider it impossible for the Japanese to win the Battle of Guadalcanal.