I think I am just dense.
So, if someone rolls a 1 controlling a monkey, the result is 1-4, or -3.
A roll of 2 results in 2-4, or -2.
A roll of 3 results in 3-4, or -1.
Given the Core Rulebook, "If penalties reduce the damage to a result to less than 1, a hit still deals 1 point of nonlethal damage." (179).
Thus, a monkey can never do better than -1 and so always deals 1 point of nonlethal damage, provided it hits?