Both of your provided links clearly show and talk about using valve rotators. Valve rotators are not used in performance builds, so valve rotation is not supposed to occur. If it does, something is wrong.
Lack of rotator does not indicate that rotation should not, and does not occur. A key or pin would.
Read it again: The cdx link I posted goes so far as to state, "some engines EVEN use positive rotators."
Op should be concerned for the fifteen not rotating, Not the one that does. This is not a function of cam type, or even valve actuation design. It's inherent in the function of the poppet valve. Paint the stems, run the engine, talk to your head builder.