Other specifications have text that appears to assume interceptors will run for non-contextual instances.

The PDF (and CDI 1.0 for that matter) list the following rules to be considered a business method:

7.2
Container invocations and interception [biz_method]
When the application invokes:
• a method of a bean via a contextual reference to the bean, as defined in Section 6.5.3, or
• a business method of a session bean via an EJB remote or local reference,

and then say:

If, and only if, an invocation is a business method invocation:
• it passes through method interceptors and decorators, and
• in the case of a session bean, it is subject to EJB services such as declarative transaction management, concurrency, security
and asynchronicity, as defined by the EJB specification.