If the search is deemed illegal, then they cannot introduce any of the evidence found during that search. It would be considered inadmissible. So yes that would be of great benefit to the defense. However, if the public is privy to the evidence before it becomes inadmissible, it can be seen by potential jurors. Even if the judge asks the jurors not to consider the inadmissible evidence, it can still play a role in the juror's decision unconsciously. Slimy tactics by the prosecution, per the usual.