So that there would be no trace of the forged documents on his or her personal computers. Why forge a document on your own computer when you can use a public computer, right?
I know that data can be retrieved from a hard drive if it has been deleted by Windows, or whatever operating system it's using. There are programs out there that can "retrieve" deleted data, but I'm certainly no expert.
Any Freeper computer experts out there that can back me up on this?
I've rented computers at Kinko's recently. It is a very restrictive environment. I imagine the files get wiped when you log out. But, the apparent haste with which the forged documents were created is suggestive of a rented computer.