"if it is democratic that the unionist minority in present day 'Britain' have a right to decide that the border remains in place, it is equally democratic that the British people have a right to decide their involvement in maintaining that border"

But we don't care Jim.
It is up to them.
We will be very happy when they decide to go, but meanwhile we will defend their right to choose.

"it has been put on the back-burner for the sake of peace "
Peace is what everyone wants Jim. Why do you want to change it?