Inclusion is a condition: what something is.
Including is an act — something including itself in what it is. Inclusion is what that act establishes: the persistent condition of what something is. The distinction matters throughout the derivation. Acts happen; conditions hold. Including does; Inclusion holds.
Inclusion is forced because negation is determined by how it relates thing and equivalence. From this determination, negation cannot not derive dynamics of relation — the conditions through which things stand to one another. Inclusion is one of these conditions: the stable “what something is” that negation works with when it distinguishes something from what it is not.
Paired with Exclusion, which is the condition of what something is not. Together, Inclusion and Exclusion are the two conditions forced by the dynamics of negation.