A bastardization of two contradictory terms. True Blue is a dated naval/sailing term meaning honest and loyal to a unit or cause. Blue Falcon is used in the modern Army to designate a "Buddy F**ker", that is someone who is not a team player and displays no unit loyalty. Implies a more negative meaning when the terms are put together in this way: True(as in real,bigtime) Buddy F**ker.
Seaman Smith is True Blue. He took a cannonball to the testicles but still managed to crack a smile when the Queens knickers caught fire.
Private Tickle is a Blue Falcon. He ate a piece of pie at dinner chow and the drill seargent smoked the whole platoon.
Private Englund is a True Blue Falcon. She f**ked her country.