Does section 1009 of the California Criminal Code protect a defendant's right to due process?

"[S]ection 1009 protects a defendant's right to due process." (People v. Pitts (1990) 223 Cal.App.3d 606, 904, superseded by statute on other grounds.) Section 1009 provides, in relevant part: "The court in which an action is pending may order or permit an amendment of an indictment, accusation or information, or the filing of an amended complaint, for any defect or insufficiency, at any stage of the proceedings . . . . The defendant shall be required to plead to such an amendment or amended pleading forthwith, . . . and the trial or other proceeding shall continue as if the pleading had been originally filed as amended, unless the substantial rights of the defendant would be prejudiced thereby, in which event a reasonable postponement, not longer than the ends of justice require, may be granted. An indictment or accusation cannot be amended so as to change the offense charged, nor an information so as to charge an offense not shown by the evidence taken at the preliminary examination."