Since time is, as far as we know, infinite...why wouldn't a book that holds every single page of every book ever written...be infinite in weight? As it also stands, from what you said, he did lift a book that should be greater in weight than a planet.
Goku dropped from the skies with 40 tones attached to him. Well now...
Love the nitpicking. Let's keep at it :D.
I don´t see it as nitpicking. I love both characters and i am a fan of death battle, i just want the outcome to be true. Super getting beated by Batman will annoy me way more when the move releases.
About the book, it is open to some interpretation, no doubt. But the by the letter would be the book having all the books written in the time spam of that universe, and another 52 multiverses that coexists with that one. Which does mean an incridible amount of weight, most likely more than 1 planet, but not ALL the weight, as Death Battle made it look like.
Also Shazam was there, and Death Battle said that he didn´t need to. That´s absurd, as Shazam is many times showed to be just as strong as superman. When they did an arm wrestling (i believe that´s the name) they remained in a tie for hours, until Mary Marvel and Marvel Jr. has to transform, which drains some of the Cap. Marvel powers. They all share the same power sorce.
Finally, Shazam states that he has a machine of some sort that can scan all info from the book, which it is why they try to carry it out the first time i believe. That also points to the book having a finite amount of weight, no matter how large.
I don´t know about the 40t rock thing, is that from the last Dragon Ball movie?