"to make witnesses defensive and reluctant to say anything and just take the fifth."
That would be fantastic! The fifth applies to any testimony that might lead to criminal charges. In a criminal case, there can not be repercussions for taking the fifth, but in a CIVIL case (such as this one), the plaintiffs can actually use a party taking the fifth against the defense.
McCarthy v. Arndstein (1924) Baxter v. Palmigiano (1976)
If they haven't been unethical they have nothing to hide! We are not discussing war time discretion- we are talking about business/financial practices along with moral and ethical practices. No one should be above the law! No one, no exception! Your thinking is dangerous.