These statements date from a time when we thought assistive technologies might use epub:type semantics like ARIA roles:

The inflected semantic MUST express a subclass of the semantic of the carrying element. In the case of semantically neutral elements, such as the [HTML] div and span elements, the inflected semantic MUST NOT attach a meaning that is already conveyed by an existing element (e.g., that a div represents a paragraph or section).

We have recommendations on what elements to use the semantics on in the structure vocabulary, but these have never been enforced and were always meant as guidance. In other words, they don't even bear out these requirements.

I don't see the harm in making these statements informally, so switch these to lowercase should/should not.