It IS correct say that. Ceres is still an asteroid (or like the IAU says, a minor planet). Pluto and Eris ARE Kuiper belt objects.

Otherwise the term "dwarf planet" would be contradictory: If they're not members of the belts, then why they're not true planets?

EDIT: Argh, now I read the IAU Q&A... I think it's wrong. "Asteroid" means "minor planet" (despite that Wikipedia claims otherwise). When the Minor Planet Center assigned Pluto a minor planet number, they mentioned that objects can have dual classifications (there are a few asteroid-comets). So Ceres is a minor planet, as is Pluto. Ceres it is a dwarf planet, but it is also an asteroid (unless asteroids = small solar system objects sans comets).

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