Banks are not law enforcement and should cooperate with the authorities when someone is breaking the law or is suspected of doing so.
Banks should operate based on Standard Operating Procedures (SOPs) and policies which should be voted on by shareholders when it affects who they do business with. Lots of banks have traditionally restricted the types of businesses they offer services to. For example, many banks avoid dealing with risky businesses like gaming/gambling. Many do not offer services to adult entertainment businesses.
The important thing is that they should not operate on the whims of management.
Banks should be treated as public accommodations and should not be allowed to deny service to individuals for political reasons. (Political views are not the basis of a protected class of people currently, but they should be.)
Re your expanded comments on banks.
“Public accomodation” is the key word here.
Banks are public accomodations. So are super markets. But, not in my opinion, custom cake makers or photographers.