NeonZ
Member
The idea that a Genki Dama can't be charged in Super Saiyan wouldn't be something the episode writer would be allowed to decide, that'd be something decided by Toriyama, the series directors or the producers.
That's assuming it was an overall brand direction rather than just the episode's script writer throwing a line there he thought was appropriate. Dragonball Heroes added a SSB Kaioken Genki Dama almost at the same time as the anime version, but there Goku charges it in SSB.
https://youtu.be/NZ4jUS4O9r0?t=29s
So, the idea that he can't charge it in SSJ doesn't seem to have come from the top.