Why did Pope Innocent III want Sicily separated from the Holy Roman Empire?

Pope Innocent III sought to separate the kingdom of Sicily from the Holy Roman Empire because any ruler who possessed both crowns posed a direct threat to the Papal States.1

Following the death of Emperor Henry VI, who had subjected both the Italian peninsula and Sicily to his rule, the papacy feared that Rome would be engulfed by imperial power. To prevent this, Innocent III worked to maintain the integrity of the Papal States and ensure that the Sicilian kingdom—a papal fief—remained independent of the German empire.12

Throughout his pontificate, Innocent III attempted to enforce this separation by exacting promises from imperial candidates, such as Otto IV and Frederick II, to respect the boundaries of papal territory and keep the administrations of the two realms distinct.31