Interpretation is exactly why nothing beyond "Not Ripe" has any legal bearing. Just as USAPA interprets the quote above, and others like it, in whatever way they choose, so can a person submit an equally valid yet opposing interpretation.
ALPA was not free to abandon the award without consent from the west. Therefore, USAPA is "as free to abandon" it as ALPA, which is to say not without consent or agreement from the west. Since there is no more west from which to obtain agreement, USAPA is left with little choice.