Sure there was some cheap USA stuff. That's kind of like the "you suck" chant during Angles entrance, it is so ingrained people can't help it lol.but the heat he got wasn't just people booing the booking. It was a mix of both that and the ones reacting to the anti American cheap heat stuff. there were "USA" chants etc. as I said, so the anti American gimmick was still part of his heat, as was just the undeserving aspect. and people legitamely despised the character regardless of if it was booking or go away heat or however you describe it, the hate he was getting helped get AJ more over at the time in his career as a babyface. I'd even go as far to say that Jinder vs. AJ was the better match between that and AJ vs. Nakamura due to AJ winning the title, making history of winning in the UK, and the fact that AJ vs. Nakamura simply didn't live up to the hype at Wrestlemania. the angle was built around low blows and Nakamura's newfound heel character, while AJ vs. Jinder was a classic 80's style David vs. Goliath match which resulted in AJ having a memorable title victory.
I do agree that Styles vs Nakamura was not what it could have been. I think a lot of that had to do with Nakamura losing a ton of his momentum by losing to Jinder. They didn't build up Jinder at all, so it felt like Nakamura couldn't beat a jobber.