If you read in the arguments he is willing to comply with the pen register but the FBI argues that the SSL keys are required for this to function. Based upon my

If you read in the arguments he is willing to comply with the pen register but the FBI argues that the SSL keys are required for this to function. Based upon my understanding this would mean that the pen register would use the keys and essentially pull a MITM attack on all traffic or the FBI just really doesn't understand that the mail wasn't encrypted once it hit the server and if their pen register functioned after the SSL termination they could get what they wanted without the keys.