It seems to me that this is a classic Vatican-style political move. Garza resigns as Vicar General of the Legion in order to take control of the new “Legion Territory of North America” which has conveniently been created by consolidating the operations formerly headquartered in New York and Atlanta. That way, he is removed from his key position in Rome, to accept a new, "important" assignment without “losing face.” Meanwhile, the former territorial directors, Fr Julio Martí and Fr John Connor, are moved aside.
Fr. Connor, especially, stuck me as one of the few senior Legionaries who demonstrated a practical, almost humble, approach to the Maciel scandal. At a fundraising event for the Legion at the Waldorf Astoria several months ago, he was the only one of many LC speakers, who openly acknowledged the 800 pound gorilla in the room - the awful scandal caused by Marcial Maciel, the founder of the Legionaries. It remains to be seen if this move is also designed to manage internal dissent in the United States.
While Fr. Garza has formidable skills, management experience and powerful connections to contribute to his new job, I suspect that this is really a transitional move designed to begin the process of dismantling current senior LC leadership. Fr. Garza can claim not to have been demoted. He will initiate serious damage control in the all important territory of the United States. His prestige, especially back in his native Monterrey, will not be perceived to be diminished.
Fairly predictable Vatican politics. It just took longer to happen than I expected. Look our for similar moves in the near future.