The fulcrum on the ground is the maingear axle. Backstick produces down force at the tail which:
- Adds to the total load on all gears
- Produces a nose up moment which relieves a portion of the load on the nose gear such that the maingear supports a larger portion of the total weight plus any aerodynamic downforce.
This may result in a change in AOA and lift, but as certain pilots have found this technique useful on certain types, it stands to reason that there remains a substantial net benefit on those types.
The military, certainly in Overtalk's case, often has a more nimble organisational culture that allows researching and promulgating new techniques at a faster pace than do the airlines and the regulators. Improvisation when you're the only one in the a/c is a quite a different matter than when there's a few hundred people in the back. I do hope the manufacturers, regulators and training departments pick up the ball on investigating what appears a promising technique.