The assertion is outdated, i.e. there is no corresponding text in the spec. And the interceptors spec, 3.2 Declaring Interceptor Bindings of an Interceptor, only states:

With the exception of AroundConstruct lifecycle callback interceptors, an interceptor for lifecycle callbacks may only declare interceptor binding types that are defined as Target(TYPE).

However, it's not clear what should happen if a violation occurs (see also https://java.net/jira/browse/INTERCEPTORS_SPEC-22).