Furthermore, the actual canonical history beyond Endor does take account of the Alliance's difficulty with holding together. Mothma and the Council ended up making massive decentralization concessions compared to the way the Old Republic had done things. And even then, the New Republic had a hell of a time holding together, and basically relied on the Fleet for its survival at several points - confronting Thrawn and the Dark Empire, dealing with the Yuuzhan Vong (and failing to deal with the Vong), and, in later incarnations of the Republic, dealing with their own varieties of Separatism and, ultimately, the resurgence of a Sith-ruled Empire. Politically, the New Republic and its successor, the Galactic Alliance, didn't work. At all. Which addresses his concerns with it fairly adeptly, no?