I think the recoveries team would "prefer" him to mail them using the original Email address but he still stands a chance of recovering his account using a signed message from a staked bitcoin address. They will probably do further investigations like look into the IP address logs before and after the change of email address.

Use of Original email address comes in handy when one does not have a staked bitcoin address. Once one loses control of their email address too, then there is completely no way to prove ownership of the account.