First, I do not own the Televue adapter and I don't know if what I am going to post is going to work or be valuable, but I though about it and thought I would suggest it to people using PVS-14 and TV adapter.
One of the things that I would dislike about using the TV adapter is the need to thread the PVS-14 on to the adapter.
It occurred to me that it might be possible to eliminate the need to do that. What someone might want to try is to use the snap on connector for the 3x afocal lens and mount this to the top of the TV adapter. When the snap on connector is unthreaded from the 3x lens, it has the same thread at the lens side as the front thread on the PVS-14 or ENVIS objective. This means that it should thread right to the top of the TV adapter.
Now, to mount the NV device with ENVIS or PVS-14 objective, you could just shove it into the splines on the snap on connector. I would think that the O ring in the snap on connector would provide more than enough grip to hold the NVD in place.
Again, I have not tried it, but it might be something that someone would want to test out.