Why does the second explanatory noun carry coordination in tawshīʿ?

Iṭnāb: Clarification after Ambiguity, Tawshīʿ, Repetition and Īghāl

• It turns separate statements into one conditional answer
• It necessarily revokes the first noun’s relation
• It links two nouns as the explanation of one dual
• It excludes a special member from a general class