[Tool] SafetyNet - Keep Office 365 Mailbox when removing AD-Synced user.

What do you see as the advantage to this over marking the box as an inactive box (litigation hold then removing the license)? I would typically tell the client to maintain the on prem acct for 30 days to allow for normal mailbox access for management and then mark the box for litigation hold and remove the license to retain the data when they remove the user.