I think that after we hear for Huber the Mueller report will itself be 'Exhibit A'.
All the timestamps show is that the files were copied to a FAT32 file partition (probably a USB drive) using the Linux cp command at some point before being repackaged in a zip file and sent to Wikileaks. They do not show that this copy was the initial copy from the server. Someone could have retrieved that files gradually, saving them on their local machine, and then copied them to a USB drive and it would have produced that exact same forensic signature.