There is a statement in 8.6.8 that indicates that if CBS is support, the default configuration is to be set per 34.5. The specific text is, "In implementations that do not support the credit-based shaper transmission selection algorithm, the recommended default configuration for the Transmission Selection Algorithm Tables is to assign the strict priority transmission selection algorithm to all supported traffic classes. In implementations that support the credit-based shaper transmission selection algorithm, the recommended default configuration for the Transmission Selection Algorithm Tables is defined in 34.5."
The second sentence is considered erroneous and the intention is that if you plan to use CBS and support it, default the configuration as in 34.5, but not just because you support CBS. CBS requires certain configuration parameters to be set in order to operate properly. The default settings would simply cause all traffic to be dropped.