It's been explained way too many times, including by those who actually worked at at the bank, and actually were involved IRL. It's a securitized instrument, already sold. The "safe harbor" protects the purchaser of the instrument, not the bank.
I understand it, and that's satisfactory for me. If you're not satisfied with your understanding, that's fine. It's OK even to mis-understand it.
.... Please, just call me Catz ;) - - - - - {and the requisite, all IMHO, do your own due diligence, and make your own investments}