Whether you agree with his methods or not, there is no stretch of the imagination that makes prison for downloading (even 114k of) them make sense.
It wasn't a hole or bug— it was an expressly implemented feature. ATT decided to do it this way to reduce resubscription friction. The iPad sends the sim serial (ICCID), and ATT sends the HTML form with the email address already filled in, so all the user has to do is enter the password.
As it turns out, ICCIDs are sequential integers.
It should always be perfectly legal to access a remote computer system via a publicly accessible interface. It's up to that remote system to respond appropriately. In this case, it was working exactly as ATT intended.
Weev knew that the greater the number of records he got, the worse it would reflect upon ATT, and rightfully so.