The villains, (SEELE) a secret organization who secretly control world governments, want to fuse all humans in to one to bring back their satanic god.
Now look at whats happening. They want to fuse men and women with transgenderism and nonbinary shit, they want to fuse countries and remove borders and create a one world government and they want to fuse races with race mixing.
If you know your esoterics, Fulcanelli's master supposedly became an immortal being by transforming into an androgynous form that was neither male nor female. Considering how hard the global elites bought into that shit a century ago I suspect that this is more what they're in line with. Either that or my original theory that the aliens are gay androgynous space communists and only help out species that are androgynous space communist enough, so the world leaders are falling all over themselves to make it happen.
I find your original theory lacking to be quite honest.
I find the UP3 theory from Star Ocean series to be more convincing. Advanced star faring civilizations choose to not make contact with less advanced civilizations in order to preserve their authentic development.
If humans manage to reach out to galactic federation then that means they meaningfully united on their planet and pulled all their resources for a single unified purpose and devised methods unique to them to do so.
If humans wont manage to reach out to galactic federation then that means there's no point in bringing them into the galactic forum as whatever that is dividing and stalling human progress would likely affect the greater galactic society as well.
Most likely, aliens don't exist
The plot is trying to reunite the angels Adam and Lilith. It's unification propaganda