Although he also gained a seat on the Politburo at the same time, the overall direction of ideology and propaganda work was 'supervised' by Standing Committee member Li Changchun; thus Liu was, for all intents and purposes, not the top propaganda official in China at the time.
While he gained a position on the Politburo concurrently, the overarching control of ideological and propaganda efforts was overseen by Standing Committee member Li Changchun, making Liu effectively the second-in-command for propaganda within China at the time.