A part may be conceived as prior to the whole that comprises it. The rationale for presenting majāz before kināyah draws an analogy from this part–whole relation.
The limit of that reasoning matters. Kināyah is not literally concomitant + antecedent as a composite containing majāz as a proper constituent. The point is that both involve the associated intended sense, but kināyah has the additional permission of literal intention.
Thus “part before whole” supplies an explanation for the order of exposition, not a rigid new definition of kināyah.