I don't think this can be correct:
 
EAP-Message is used between  NAS and FreeRadius to encapsulate the EAP protocol between client and server.

The NAS couldn't tell that a particular EAP-Message should terminate at itself in order to extract an MSK; it would just de-capsulate and pass the payload to the peer (functioning as an EAP proxy).

Notice the Zorn draft RFC doesn't use EAP-Message; it puts an encrypted MSK in an extended attribute.
This kind of makes sense since it would be clear to the NAS that it is the intended termination point.

My question was how is it done today in the field (pre this draft becoming and RFC).