It's interesting since the grand jury and DA won't indict, he may not have the privilege to take the 5th if there is no longer a reasonable fear of incriminating himself and exposing himself to prosecution.
Even so, he has to defend himself or it's simply "she said (no he said)" for the jurors to hear. Also, at trail, they may be allowed to draw a "negative inference" from his taking the 5th in deposition.