The judge's ruling to suppress the confession as inadmissible would have been easily overturned on appeal. The US Supreme Court ruled in in Rhode Island v. Innis, (446 U.S. 291) that a spontaneous statement such as the one the officer described is admissible so long as it was not as a result of police questions.
When Jaime and Brenda first arrest DeMarcus they hand cuff him with his hands behind his back. After he escapes and they later find DeMarcus (at 15:30) his hand are cuffed in front of him.
Police recruits for the NYPD undergo an extensive background investigation before they are hired. It is not possible that the criminal background of the immediate family of the officer would have gone undetected prior to her being hired. As such, the IAB would not have the leverage on her to make her a field associate.