Um ... hadn't considered that about active waypoints, and can't remember offhand how exactly it behaves. However, I'm not convinced that an FMGC derived position - can think also of a time marker, TOD or step-climb marker - would actually show as the next active waypoint on ADS-C.
And isn't part of the point about MNPS airspace (which is when ETP is most useful) that you don't have radar monitoring?
I have to say that I have very limited experience here, so these are genuine questions.