Aw, com'on Mongo! Nothing at all Vague about that item. The Safety Code Turbine Section references to document 513, Turbine Safety Rules. In there you find that the safety rules are applied to both CL and RC aircraft and maybe for FF. (I wasn't looking for FF. [:-])
The item states RUDDER for all RC models. Without having to restate every already-stated word, the rule simply states that rudders are required on RC models and NO REFERENCE is made to CL etc. Doesn't say can or can't for those other than RC.

In the turbine document where CL and RC are addressed and specific to RC.

If that rule is vague, then so is just about everything else vague to you, except maybe "Time to eat."