complained about the fraud. I highly doubt that. Just because banks did not sue him directly does not mean that no bank reported fraud to state authorities.
Typically fraud is reported directly to state or federal authorities and banks let them take the lead because CRIME is involved.
And my experience is guarantees are only “offered” because the underlying loan won’t be acceptable risk at acceptable pricing unless a strong guarantor is needed by the lender. It’s offered for concessions from the lender.