I can't agree with this statement either. The best case scenario would have only made the war start later.
Taking the Neville Chamberlain approach would have only emboldened the Japanese towards their next conquest. Likely if they wanted to avoid immediate war with the United States it would have been by joining their Axis partner by attacking the British. This would mean an attack on Singapore.
With Singapore gone, it would have opened the doors to the Dutch East Indies.
Eventually, the United States would have had to respond to this expansionism and the only way to stop it would have been war.
I think the prospect of Japan ever joining the Germans in an attack on the Soviets was never a realistic prospect. If it was they probably would have done so from the moment they reaffirmed the Tripartite Pact. I think the battle of Nomonhan really set the stage for that and Japan (and the Kwantung Army) wanted no part in fighting Soviet Siberian Divisions.
Note my response to PeterPrinciple, I think it answers most of your points.
Remember, the Japanese negotiated in pretty good faith as long as they believed a peaceful solution was possible.
So if FDR had offered the Japanese a non-aggression treaty, wherein the US fleet returns to permanent station in Los Angeles, and US forces in the Philippines stand aside while Japan has it's way with French, British and Dutch colonies, the President could have bought us several more years of "peace."
After that, who knows, it's all speculation, but we know Roosevelt died in early 1945, and Hitler was in very poor health, so by 1950 at the latest, there would be a wholly new cast of characters, and who might they be?
But please don't misunderstand my speculations here -- I think President Roosevelt did exactly the right things (with some exceptions I've mentioned), and deserves all the credit for America's success in the war.