In what circumstances will a self-represented defendant in a criminal case refuse to object when called as a rebuttal witness for the prosecution?

^5. We acknowledge that, unlike here, the self-represented defendant in People v. Barnum failed to object when called as a rebuttal witness for the prosecution. However, this distinction takes nothing from the high court's otherwise relevant observations with respect to the lack of harm suffered when "the prosecutor, in effect, merely subjected defendant to reopened cross-examination [citations] or recross-examination [citations], doing little more than what he properly did on the initial cross-examination of defendant in the court of the defense, which was to impeach defendant's credibility by probing into prior incidents . . . ." (People v. Barnum, supra, 29 Cal.4th at p. 1227, fn. 3.)