I think the implication he's making is that a benevolent dictatorship would be more effective than a corrupt democracy – which is probably true, but only if you're making the assumption that the dictatorship will continue to support your interests in the future.
One good way to keep them good is free speech to be able to publicly shame them. If you decide to violently overthrow them, free speech helps you organize opposition.
I think the implication he's making is that a benevolent dictatorship would be more effective than a corrupt democracy – which is probably true, but only if you're making the assumption that the dictatorship will continue to support your interests in the future.
I'll take a good king over a corrupt council any day. The problem comes when the not good kings start showing up.
One good way to keep them good is free speech to be able to publicly shame them. If you decide to violently overthrow them, free speech helps you organize opposition.