Maybe it helps to consider all 4 possibilities for the sign of the gravitational mass of antimatter, and the sign of the inertial mass of antimatter?

(-,-): antimatter would fall down, but we could break conservation laws with a mechanism.

(+,-): antimatter would fall up, but we could break conservation laws with a mechanism using electrically charged particles.

(-,+): antimatter would fall up, but ruled out by the experiment.

So what remains is (+,+)?