Factual error: The type of book that Eli is protecting would actually be just a fragment. The complete Bible, in braille, occupies as many as 18 volumes.
Factual error: Eli uses an apparently moist KFC wetnap to clean himself in an early scene, yet it's been at least 30 years since the apocalyptic event happened. Unopened wipes only stay moist for months, even big packets of baby wipes only stay wet for 2-3 years.
Answer: Most likely, Redridge is giving Solara a chance to escape Carnegie's regime. At this point, he knows he's dying, but perhaps still wants the best for her. Remember, he had a crush on her the whole movie (blocking her while she was getting Eli's canteen filled, bargaining with Carnegie for her before chasing after them, even asking Eli nicely to give up the book after the gunfight in the house). I think it may also have been used as a self-redemption moment for one of the bad guys.
Jason Sieberg