Narrative theology begs several important questions. Perhaps the most important question is if there is no absolute truth or meaning to the Biblical text, then why should a person care about the arguments made by those who advocate this form of theology. Their perspective is just as subjective, and therefore, worthless, as anybody else's.
If there is no objectivity in interpreting any text in the Bible, then (say) a sign saying, "Danger High Voltage," might mean that a French gourmet restaurant is nearby, and not that a hazardous amount of electricity might electrocute the careless.
If authorial intent does not matter at all and is indeterminable objectively, then anything indeed goes with Narrative theology (and a host of liberal sacred cows is slain with the general epistemological wreckage coming from deconstructionist literary theory). Hence, if there is an objective interpretation of (say) a biology textbook, there can also be one (in principle) of Scripture using the grammatico-historical method of interpretation and objectively based hermeneutics.