I don't think his right-wing extremism can be explained away as a reaction to FDR or the impending war, since it goes back quite a bit earlier. He published The International Jew: The World's Foremost Problem in 1920! It was actually the inspiration for parts of Mein Kampf (1923), which speaks approvingly of Ford and lifts some sections more or less directly from him. And, he met with and corresponded with Nazi representatives several times in the early-to-mid 1920s, a point at which the Nazis were a fringe extremist party not anywhere near government, so couldn't plausibly be said to be part of normal business ties with Germany. I think he just kind of hated Jews for some reason.
It's always worse to look back and compare the actions of someone 100 years ago to what we would consider normal today. I'm not forgiving the guy, but you'd have to look around at some of his contemporaries and see if this type of behaviour was normal. Going further back, a lot of well-regarded American had slaves, for example.
A lot of people were friendly with the Nazis in the early-mid 1930's. They did turn Germany around and get it going in the early stages.
Yes, that's fucked up and sad. Maybe all his success went to his head. My point was that not everything he did good should be cast in the bad light, for instance, a person wanting to run a manufacturing business could gain a lot from taking his advise. I'm not an apologist, just think there is value in reading about extraordinary people.