This is awesome, no tricks to remove her powers, just taking ownership of her powers and all. There is nothing more erotic for a powerful woman than being helpless, with all of our power still present but useless.
Good stuff. He needs to train her lots more. And then help him rape Wonder Woman.
Just like your Wonder Woman story, this is too short and lacking in humiliation. Could've used a lot more sex and degradation, like him training her to become his obedient Superbitch.
And since this guy is the president of the film club why not write at least one chapter that features Supergirl as an amateur porn actress?
Plenty of options!
Sexy, want more of this story. She needs training!