The pieces to construct the ninth missing color combination perhaps isn’t present to get antimatter, which means antimatter isn’t created. On the other hand: we would otherwise only had photons in our Universe (I’m not specialized in quantum mechanics though).
I like to clarify again, that a collision of regular matter with antimatter creates photons, while the formula is about relativistic mass and not relativistic energy.
The lack of antigravity would even make it more comlicated, if the above wouldn’t be true.
We could maybe store antimatter in a tokamak though.