Considering he was added in the first ten episodes of the anime, you can't really call him "last minute". Just because characters were added into the anime doesn't mean they were thrown in without thought being put into it. Hakim existed as a character to mirror Hachimaki, from his relationship with Gigalt through the Von Braun project and in regards to life in general.
Hakim was someone who worked himself up from nothing and threw it all away, nothing more than a footnote in history and fugitive for the rest of his days while Hachi will probably go down along the likes of his father, Gigalt and Henry Rowland as greats of space exploration.
Outwardly, at first Glance Hakim had everything made. Suave, good looking, skilled, a promising career in the military, candidate for the Von Braun program, etc. Hachi was a hardscrabble garbage collector and a piss poor attitude. But Hachi had his dream and Hakim was just full of jealousy. He and Claire were already perfect examples of what their peoples could rise to and they threw it away. At least Claire can redeem herself but Hakim never will.