Does the Esteban biography disagree with history? Not really. Although it does disagree with the conventional history of him. Even though almost every account states without reservation that Zuni natives killed Esteban in 1539, the biography points out that such a death was based only on assumptions by Mexican Indians reporting to Friar Marcos who admitted they didn't see it happen.
Actually, nobody knows for sure what happened
Future writers of books involving Esteban should note that there is more than one possible outcome for Esteban instead of just declaring that Zunis killed him — because there is no proof that they did, and there probably will never be proof one way or the other
All that can be known for certain is that, for whatever unknown possibility, Esteban disappeared from the historical record in 1539.