Key to your statement...a LEGAL subpoena.
Congressional subpoena’s are not an instrument of the judiciary.
We used to clear all this stuff through the army of attorneys in our compliance office. It was never up to “us” to make that distinction. You might be surprised at how often we would meet our Secret Service, FBI, and State Police buddies.
The problem here is that is not up to US (you or me) to decide, but rather the banks legal staff.
With Nadler and Shitt threatening arrest by the Sergeant at Arms and jail for contempt of Congress, plus the additional threat of $25K per day fines, it's hard for a non-Executive Privilege person or firm to say, "Nope".
It's easy for us to say fight them, but they're afraid they can't win such a fight, and to fight, it will cost them a lot.
Prove me wrong (not that they can fight, but that they'll see it our way).