If you just want to tinker, go ahead. But if you are trying to improve the performance of your arrow, this is very likely an exercise in futility as you will not be able to see or measure any benefit that may come from dropping 10 grains and adding 0.x% FOC.
In my mind the FOC isn't really relevant. However, since he's running a lighted nock I don't think this irrelevant.
If you picture a deflection scenario - the tip is no longer in plane with the mass & associated momentum of the rear of the shaft is still going the original direction. The is more force at the same distance on the lever arm. The physics works that if you have less mass in the rear of your arrow, in theory your reducing the magnitude of the deflection and the shaft isn't driving straight. Losing penetration as well.
Secondly, on a hard impact where the system is coming to a near complete stop in a extremely small distance and time. Causing a large impulse and dispensing of KE & M. Picture it like setting up the spine of your shaft at launch out of your bow. The larger the force in the draw force curve, the stiffer spine you'll need. An aggressive cam at 70# might need a stiffer spine than a normal 70# etc. Key here is thinking about it like going from a 125 to 150 grain head. It might cause you to be weak in spine.
Now on hard impact - the mass of the rear of the shaft and mass of the shaft itself is what is going to cause deflection. Opposite of at launch. The 30ish grains he sheds losing a wrap, lighted nock, and going with slightly lighter vanes is reducing the magnitude of the deflection and keeping that arrow driving home.
Same goes for a mechanical when it deploys. It's dispensing a lot of energy at impact to deploy the blades. If you've got a stiffer shaft if's going to deflect less and keep driving. If you have less weight out back it's going to reduce the magnitude of the shaft flex.

In my mind, keeping the rear shaft weight low to increase penetration is easier to logic my way through than increasing FOC. I just stick with normal weight nocks, minimal wrap if any and 6-7 grain each 3 fletch for this reason.