If he "starts over" he is in same boat as the other folk without income letter.
To use income method he would need to show 12 monthly transfers.
For that reason you see those starting over or just obtaining Non O retirement for first time ....use money in bank method.
Will be useless in start over process
Edit: one caveat.... immigration may cut some slack. Perhaps only requiring 6 month of transfers for next extension.
Thinking something like this occurred back in 2018/19 when letters were dropped for UK,USA, AU citizens