Edit: The prosecution was explaining why the Zaminsky's weren't on the stand, asserting they had a 5th Amendment privilege. However, it is untrue for the wife.
But when it came up, the judge looked furious. They argued a bit, the judge thought about it, and found a solution.
If he'd let the two sides to get into it, it would've allowed the possibility of giving the defense a rebuttal. The judge found a way to avoid it.