Ok let me rephrase that - I found watching his storyline very interesting. The guy himself was a loser, sure, but I think that subplot and all the interactions it contained said a lot about the way different cultures react, especially in a colonial/imperial setting. The way the people in the conquered culture imitates the conquerors, assuming them to be superior, and the way people in the conquering culture fetishize and commodify the culture they conquer (look at the way the British treated their colonies). I thought it was a really nice touch from a worldbuilding perspective.
They were clearly reaching out for him as expert on American culture and wanting someone to help them be a little 'bad.'
I guess I saw it slightly differently. They were definitely trying to be a little rebellious (the "negro music" and whatnot) and he wasn't willing to play along because as a white guy he couldn't afford to be seen indulging in anything "degenerate," (although he did give her the flapper shoes to suck up to them) or perhaps was trying to maintain a cultured image, but I got the impression the whole point of the exercise was just an opportunity for them to examine him up close and grill him about American culture. He completely missed the point and thought they'd invited him as a social equal, because he was desperate for Japanese approval and missed all the social cues and hints (like them inviting him and nobody else, and having the dinner so early). This all went over his head until they refused to make a followup dinner and hustled him to the door (and more or less outright stated that they just wanted to examine him and quiz him), at which point he finally realized they were treating him exactly like the artifacts they collect - as something interesting and exotic to examine, but not a social equal, or really any kind of equal. I don't think they were trying to mock him as such - you don't mock an animal in a zoo. I think that's closest to how they saw him (and probably reflected how most Japanese saw the Americans - like with the Prince at his speech "or as you say in America, "howdy!"") A pet American - able to let them indulge in their fetish but inherently not on the same level as the Japanese. He, on the other hand, took the Japanese custom he received as a sign of their acceptance, and tried to enforce that impression by adopting their behavior.
So yeah it was awkward and cringe-worthy, but I think it made a lot of really interesting points. It was more interesting than any of the resistance crap anyway.
That's the other thing I found weird. The Nazi's got really shitty at Joe for helping a member of the West Coast resistance, but she was a white woman in a resistance group fighting to free primarily white people from the rule of the Asian Japanese. I get that they had a tentative truce with Japan and had granted them "honorary aryan" status, but it seems like they would be siding more with the whites on the West Coast and less with their non-white frenemies. I guess the whole film mystery complicates it a bit, but when it comes to the resistance they talk like those fighting against the Nazis and those fighting against the Japanese are equally bad, when I would have thought the Nazis would be all for weakening the Japanese