OK, so your son had is computer seized by a secret service agent who specifically said he didn't need a warrant.
If your son disagrees with this, he will need to do is get his attorney to look into that seizure and see about getting any evidence gathered from that computer removed from the criminal case against him.
However, if he was already spotted by an eyewitness using stolen credit cards, the police may not need any of that evidence.
Also, your son's attorney may be able to revisit the bond issue with the court. If you can provide the passport with an issue date of over a year ago, you can argue that the SS provided false evidence to the court.
Of course, you have to wonder WHY the SS agent would have said what he did. Did your son e-mail somebody talking about how he can skip town with his new passport? Don't waste your money on making the lawyer file motions if your son's words are going to sink his own chances.
P.S. The day that the SS agent came to your door looking for your son in connection with some federal felonies is the day he should have started looking for a good lawyer.