Well, he's an anime fan, so I doubt he meant to be racist against Japanese people. I think he just didn't realize it was a slur. It's worthy of a mod warning, but certainly not ban-worthy.
Talking about that preview though, it looks neat even in storyboard form! However, I continue to be perplexed by Unit 1's role in this movie. How is the whole thing restored to the way it was in the first two movies, even the hangar it's stored in? I'm convinced it's either time travel or another surreal vision sequence.