@dbaca Create a Restricted Software configuration, Use Migration Assistant.app for the Process Name, select the Restrict exact process name and Kill process options, add a Message explaining to your users that they're not allowed to use Migration Assistant, set the Scope to All Computers (or whatever subset of your Mac you want to block it on)
That will at least block the Migration Assistant app from running on your company Macs. It's not going to stop your users from putting a company Mac into Target Disk Mode to do the migration. For that you'd need a firmware password (or whatever that's called these days).
