It doesn’t matter if the copy is all at once. Every bit of the file touching your computer involves multiple copies. It is fundamentally impossible to share any file without copies being made. The original digitization is already probably illegal because it’s for the purpose of distribution and not one of the fair use exceptions. Again, this is exactly identical to the claim that pirate sites providing streaming is legal.
Libraries do not make copies. Legally, it’s exactly that simple. There is no ambiguity in any way. It is copyright infringement under current law. It is not possible to defend this without throwing current law in the trash and starting over from scratch. If the judge did somehow rule in IA’s favor the Supreme Court could overrule him in about 30 seconds with basically no deliberation. Courts do not have the authority to change the law.