Courtiers distrust rivals competing for his favor, breeding cautious vacuity. [causal]
There is a further problem in power relations. The subordinates may come actively to distrust one another. For example, courtiers are commonly in contest with other courtiers over who has the greatest favor of the powerful king. The French court in Versailles elevated vacuity to its high status in self-defense against the harms that could befall anyone who ventured to say anything with real content that might be reported to the king.
XREF: Connects to the broader discussion of power relations and how subordinates under authoritarian control develop coping mechanisms like self-censorship.
Russell Hardin, Trust and Trustworthiness, loc. 478