Personally I would not do that (mix with 2-part), for the simple virtue of erring on the side of caution.
Genetics, if I had to guess, he is possibly wanting to increase either "good" algae or soft coral growth if his tank is 0 nitrate.
You "can" increase nitrate with heavier feedings or heavier fish loads (or both) but you also introduce phosphates that way.
Personally I try to avoid using GFO simply due to cost, so I am considering dosing nitrate to aid my chaeto in removing phosphate. Mine is well below the .25 ppm that my API can detect, so I don't have very far for the chaeto to pull down.