He switched to a new phone and wiped his old one, and when he restored from the iCloud on his new phone the bitwallet app had a new wallet that doesn't have the bitcoins in it. Unfortunately he had not backed up the wallet file
It's gone.
The only hope you have now is to send the disk of the old phone to a forensics lab to try and recover the keys... however, since bitWallet is closed source... no one can tell you where to look except for the company that made the app.
For future reference: iCloud backups do not store identifying account data for apps... you should have noticed how after an iCloud backup restore he had to log in to everything again, and the only stuff that came over was mail accounts with iPhone's stock Mail app. Only local encrypted backups store login credentials for apps and secret data. (You have to perform a backup with your computer via USB and check the encrypt backup box.)
Lesson learned: backup now. not later.