Simon wasn't GARlock, but he had plenty of GAR moments of his own.>>9912904
He's not incapable of standing on his own. The Simon we see care strongly about two people: Kamina and Nia. He was utterly reliant on Kamina, I'll grant you that, but when Kamina ceased to be Simon broke down and was BAAAAAW, and then Nia came around and told him to stop BAAAAWing, because he doesn't need other people to be strong.
The whole second half was him not needing that one Kamina figure to be strong. Sure, it was all to rescue Nia, but it wasn't because he was reliant on Nia, but because he fucking loved her. And it was him who did it, along with the entire Gurren-Lagann Brigade.
You could argue that the inclusion of the Gurren-Lagann Brigade is another sign of him being incapable of standing on his own, but I hope you don't, because then I would disagree and be forced to remind people that he was LEADING them, which needs a hell of a lot of standing-on-his-own, as well as standing-with-others. They're not as exclusive to each other as they sound.