He’d have been a fool to not have prepared his thoughts prior to testifying in front of the grand jury. Your point is....?
Preparing your own thoughts prior to testifying is one thing; allowing a lawyer to prepare your thoughts is rarely a good idea. Supposed Wilson had been indicted and had to stand trial. In some situations, his grand jury testimony may be used against him in the criminal trial, and if a skilled attorney can make the argument that the words that Wilson used are not his own, then that may very well effect the weight and credibility of his other testimony.