In two earlier episodes McGee got preferential treatment when a family member was in the hot seat. First, when his sister Sarah was a prime suspect and in another episode, when his grandmother was obstructing the investigating. See details below:
McGee's sister Sarah was treated preferentially in TWISTED SISTER (season 4, 2006). Sarah had blood on her hands matching the victim and a video showed her at the scene of his death. She claimed to have blacked out. McGee harbored his sister Sarah, did not turn her over to NCIS asap, and even allowed her to run. He only let NCIS get involved when he had no option. Even then, she was never handcuffed by anyone at NCIS and never kept in overnight detention.
But McGee immediately handcuffed DiNozzo Sr, and NCIS expected Senior to stay overnight at a prison/ detention center or wear a GPS anklet. Yet Vance insisted in taking his brother-in-law to his own cozy home. No ankle bracelet. No GPS.
McGee played a role in solving his sister's case. Not so for Tony. He wasn't allowed to help at all. This is correct and proper procedure, but the imbalance between episodes struck me.
Vance is the NCIS director. McGee is the son of an admiral. DiNozzo is treated differently when his family member is a suspect. These inequities were never discussed in the episodes.
Another bothersome episode: In this same 9th season, in THE PENELOPE PAPERS, McGee's grandmother clearly kept secrets from NCIS. McGee shouldn't have been allowed to interview or interrogate her, given their family relationship. But he did so, with Gibb's approval. Several times.