Smartness isn't fortunately a vital attribute for a leader (why, the most powerful nation of our world was led by George W. Bush for a while). What he would mostly need are a vision (a plausible enough sounding solution to the current problem), charisma (including self-confidence because nobody would follow a person who wouldn't follow himself), strength because ghouls are, essentially, killing machines and to be able to convince them, one probably needs to crack some skulls as an example, and some good people backing him up. He would have some work to do, but on the other hand he does already have a legend going for him, so he could become that legend, and he would have plenty of strength inherited from Rize if he trained himself to avoid going berserk.