Why was garibaldi a threat to the king of sardinia?

Cavour felt the successes of Giuseppe Garibaldi made him a threat to the King of Sardinia. He believed his actions might even bring on interventions from both France and Austria. An army was put together to defeat the Papal States. Garibaldi was joined by the Sardinia army against the Bourbons. Upon victory, he honored his pledge to the King of Sardinia.