I can see why future employers might find this tough to swallow. It’s a difficult thing because on the one hand you want enployees that do the right thing and are generally ethical people, and this certainly shows that he meets that criteria. On the other hand, companies don’t want the liability of having an employee that has proven that they are willing to share confidential information and documents, such as bank records, with third parties - regardless of the reason.
I hope he lands on his feet, or gets enough of a reward that he doesn’t have to work for a while, since finding work may be tough now. Doing the right thing isn’t always easy.