I'm just saying that Giratina/the Distortion World being antimatter kind of flies in the face of physics. Yeah, I know people are gonna say "lol physics in Pokémon," but when you're supposed to be the literal representation of a concept, you should at least have the concept make sense. Otherwise Giratina would explode if it entered our world in Origin Forme using the Griseous Orb, or Cyrus/the player should explode upon entering the Distortion World.
Despite what Masuda intended, it really makes zero sense for Giratina to be the personification of antimatter.