I'm Japanese, assuming that guy was referring to the use of "rice" I can advise you to just ignore him. You're fine, food isn't racist.

That’s a post hoc acryonym. The phrases like “rice rocket”, “rice burner”, etc. were applied to Japanese cars and motorcycles when those really started putting American companies and their enthusiast communities on the defensive. Whether or not that was an insult is debatable but the meaning was focused on Japan (whose business dominance was feared in the 1980s and early 90s).

Southern California had an Asian car culture which was all about customizing mostly Japanese imports, and there was a lot of debate in the 90s about the exact racial dynamics there (like other terms, some outsiders used it as an insult and some insiders wore it as a badge of pride). For fans of the early web, I’m amused to see this site is still around probably a quarter of a century after the last time I visited:

http://www.riceboypage.com/what_is_riceboy/