On the off chance that it is deliberate, I think it's fine because:
1) Time to get over it. I don't mean forget the war. But the war wasn't about food, or Japan, really. It was about cultural imperialism, facism, and a bunch of other things having nothing to do with a sushi lunch. At a certain point, like, oh, 50+ years, prejudice against food items stops being remembrance and starts being pointless hatred.
2) A sense of awareness of history. It's hard to cultivate. I didn't notice it was Pearl Harbor Day. Shame on me--but I don't think anyone in my kids' school will notice either--shame on the school. Taste and smell are powerful sensations for augmenting an experience. What better way to get kids to notice a historical event than witha taste of it?
3) They're a Friends school. Quakers have been pacifists for a little while now. I'm not into pacifism for it's own sake, and generally think a bit less of people who are. But a sect that has stuck with it through thick and thin for centuries now gets a pass in my book on this one. Still think they're wrong, but it's not a bad thing to have a few pacifists around, doing their thing.
4) Asian food is yummy. Except Korean, bleh.