They debited the case for emails? I wonder who benefited? But, your reasoning is sound. If it is closed, then no more monetary activity can be recorded. A good sign, I think.
Xlent point Streett! Billable hours! If the firm cannot charge for anything they do related to a case file, then it's locked up and adjudicated for all their concerned. The rest is just formalities and paperwork processing the sign off and request by the Trustee to the judge into the record to close the case file.