What does one see in this remark? That Genkidama having the energies cumulated of Piccolos, Goten, Trunks, Gohan, Krillin and other warriors of the Earth, is insufficient to overcome Kid Buu.
The power of Gohan (even increased other powers) is insufficient to overcome Buu.
And that, it is a fact resulting from the manga and not an impression. Now, one can always make proof insincerely.
Now what to withdraw some like conclusion?
That energy brutte of Gohan is lower than that of Kid Buu.
Those which know the series well, know that if an adversary is really more powerful than another, only one ball of energy can ensure the victory.
Some recalls:
Vegeta is more powerful than Kiwi (at this time: Vegeta - 24.000/Kiwi - 18.000). Of only one kiai, it explodes its adversary without same essouflé being.
If Gohan were really more powerful than Kid Buu, part of its vital energy would have is enough to overcome it, it is not the case