Tail moment would not provide the proverse roll couple. It's the dihedral plus a high-wing configuration. That roll couple would be intended in the design to help make it more stable for at training situation. You can get the same effect in a low-wing model if you have enough dihedral.

If you look at full-size aircraft, you can see significant differences in the amount of dihedral in low-wing versus high-wing aircraft. Both a Cessna high-wing, and a Piper low-wing have proverse roll couple with rudder application, but the amount of dihedral in their wings is considerable and very apparent visually.