Does the Esteban biography disagree with history? Not really. Even though almost every "historical" account states without reservation that Zuni natives killed Esteban in 1539, the biography points out that such a fate was based on only an assumption by Mexican Indians reporting to Friar Marcos.
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.
All that can be known for certain is that in whatever manner Esteban disappeared from the historical record in 1539.