Why should one avoid imposing an unsupported fixed meaning on “broad pillow”?

Taʿrīḍ, Talwīḥ, Ramz, Īmāʾ and Ishārah; the Rhetorical Force of Figurative Speech

• Pillows are never mentioned in Arabic
• It always changes the addressee
• Its allusive connection depends on convention and context
• The phrase lacks a literal meaning