Brining an enhanced turkey will not make it any saltier than the average of the two - the brine or the enhancement.
When you brine, liquids pass back and forth through the cell walls striving to create an equilibrium - that is, the saltiness is equal inside and out. So, if the fluids in the turkey's cells have a lower salt content than the brine, the two will equalize until the fluid in the cells and in the brine are the same.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan