The wording in section "4.1.4.1 Required" does not make it explcit with the paragraph below, that a ValueSet can be profiled and codes excluded via profiling. By using the words "may state rules", it is likely to imply business rules (ImpplmentationGuide.resource.description ) or worded documentation as opposed to a constraining of the ValueSet resource.

"When an element is bound to a required value set, derived profiles may state rules on which codes can be used, but cannot select new or additional codes for these elements."