The commentary notes that disjointness need not involve two positive species names. Two universal predicates may also be disjoint because no individual can possess both in the same respect.
For example:
Human and non-human cannot both apply to the same individual in the same respect.
Stone and non-stone are similarly exclusive.
The notes discuss related contrasts involving negation and affirmation. The essential point remains: in disjointness there is no common instance, whether the terms are both positive or one is negative.