I believe the ailerons on the 4*40 are full span as they are on the 4*60. If that's the case, who knows why they want you to trim the ailerons up. If the idea is to rig a little washout into the wing that won't give washout. Washout is when the root airfoil flies with more AOA than the tip airfoil's AngleOfAttack. Washout is supposed to keep the wing from stalling at the tips before stalling elsewhere. If you rig the entire wing, you've not accomplished that.

The wing on that design is a straight one. There is no sweep to the leading edge nor to the trailing edge. That rectangular planform is the wing layout that needs washout the least of any planform shape. It really doesn't need washout to fly better than any other planform. Whether or not it needs it to fly "better" is a matter of opinion.

Another reason might be to lessen the effects of the airplane's cambered wing profile. Guess if they felt they'd put too much "lift" into the wing, reflexing the ailerons was the cheapest way to solve that design problem.

But rigging ailerons on a cambered wing is also a matter of opinion. The fact is that rigging them "straight" gives no problems and rigging them up causes the wing to fly less efficiently (carries "more" drag that is of little value) and aileron deflection gives wider variation in effect (the excess drag on one side drops before normal drag starts).

When the aileron design is full span, rigging them up doesn't give washout to the wing. It's pretty much a waste of time for that purpose. And putting washout into a rectangular planform is also usually a waste of time. And you won't get it with full span ailerons anyway. And reflex profiles give kinky aileron response to some degree.