BMW Sirius Unit CDC-Out Plug Missing...Is It Needed?

[Driver8]

In the OEM BMW Sirius installation manual, page 8 step 20, for X5s without a CDC, the manual references a plug to cover the CDC-out port.

Below that is a warning about not using this plug, "Failure to insert the plug into the CDC extension connector could result in damage to the Sirius receiver."

I pulled the receiver out of my X5 and it did not have a plug over the port (if I remember correctly). It operated fine. I'm guessing that the plug was used to prevent something getting into the port and damaging the plugs or shorting out the unit. I didn't have a CDC and therefore didn't have the cables running to the CDC. Anybody have any ideas? Would it be possible to go with a low-buck solution (like a small strip of duct tape to cover the port and keep it free from contamination, for example) to have the same effect?

Thanks - Mike