Also devil's advocate - -
Clearly there is a distance at which a taxiway can be placed before the threshold of a runway which would comply with 8168 requirements and allow aircraft to taxi freely without reference to aircraft using the runway.
(I have no idea what this distance might be as I am not a procedure designer).
So if there is grass/sand/swamp between this taxiway and the runway threshold no one would question it.
The question is - if there is a concrete/asphalt surface between this and the displaced threshold of the runway (instead of grass) can the taxiway still be used independently of the runway?
Any examples from around the world might help PC.