I think they are trying to transfer the entire unity character database over. If they do it manually, then any time someone in the future wants to sign up for HZ they would have to email support, have them search for their character, and then transfer it manually. It might seem like it will take less time in the next month or 2 to do it manually, but it would create a huge headache for them in the future.
Automatic=good
Manual=hard work for years to come