Nobody ever said anything about immature

From Argentina: Tick, Tick, Tick by Walter Russell Mead.

“You can’t stay young forever,” says writer John Helyar, “but nobody ever said anything about immature.” Argentina seems to bent on proving his point; the most cosmopolitan and in some ways most European of Latin American countries is getting older, but its commitment to underdevelopment and economic failure appears undiminished with time.