TL,
Pushing forward is for bipods like the Harris, whose legs normally fold by swinging up and forward but have a hard stop against pressure from the rear when folded down. A bipod that folds rearward and has a hard stop swinging forward would get the opposite treatment.
This is an interesting article if you haven't run into it before.
The software I used is 3 DOF, so it does figure spin drift (the windage corrections you see in that table), but it can't figure vertical aerodynamic jump the way the Hornady software does, so I expect that's the source of the result difference. The free Lapua cellphone app has a 6 DOF solver for their bullet catalog. Harold Vaughn published a description of 6 DOF code in Appendix D of his book,
Rifle Accuracy Facts.