Justin,
I believe you have it correct, below.
National had two membership statuses: "current on dues", and not. Either one could vote, but there were a very few things that required the "current on dues" status, such as running for the LNC. Since national dues have now been eliminated, all the things that previously required "current on dues" are now folded into the "dues not required" category. M was just responding to a question I had put to him as to how national voting priveleges were affected by the zero dues changes; I thought it was relevant to your post. Nothing more to it.
All this discussion is essentially orthogonal to state/county dues. Of course, they were linked by UMP in some states, but that's another whole story...
Rich