What is the Remedy When a Prosecutor Insists a Defendant Wear Jail Garb When Testifying Before a Grand Jury?

In People v Buccina (2009 NY Slip Op 03568 [4th Dept 5/1/09])the Appellate Division, Forth Department rejected the contention of defendant that he was denied his right to testify before the grand jury where defendant refused to testify before the grand jury after he was informed that, pursuant to the policy of the jail where he was confined, he would not be allowed to change into street clothes before being transported to the grand jury.

The Court reasoned that

Inasmuch as defendant chose not to testify before the grand jury, it cannot be said that he was denied his statutory right to do so (see CPL 190.50 [5]). Further, to the extent that the policy of refusing to allow defendant to testify before the grand jury in street clothes relates to the integrity of the grand jury proceeding (see CPL 210.35 [5]), we note that, by his own conduct in refusing to testify, defendant has rendered it impossible for us to determine on the record before us whether such a policy "fail[ed] to conform to the requirements of article [190] to such degree that the integrity [of the grand jury proceeding was] impaired and prejudice to the defendant may [have] result[ed]" (CPL 210.35 [5]).

So if he did testify, would any error in the policy have been deemed harmless because he testified? If not, how could the Court determine from the Grand Jury record how the defendant was prejudiced by the policy? Phrased differently, if the policy if illegal, is there any remedy available to one whose rights are violated by such policy?