Did you even watch the show? You're right in that, for the first eight episodes, he was filled with Kamina. And then he spent the next two and a bit episodes trying to be Kamina, to try and fill the void Kamina's death left. But then in episode eleven, he stopped letting Kamina define him; He stopped trying to be Kamina, just decided to become himself, Simon the Digger. And after that, I've got no idea what you're talking about. He wanted to help Nia, for sure, but he wasn't a hanger-on of her personality, like he was with kamina. Shit, if anyone was clinging to someone's coat-tails, it was Nia.

TL;DR: Canon says your interpretation is ridiculous.