Regulation P and its parallel regulations are not a source of authority for making a disclosure. Nor are they a source of authority for prohibiting a disclosure other than an account number. All the regulation requires is that financial institutions give consumers disclosures of their practices and, if they make disclosures other than those “allowed by law” they must give the consumer a chance to opt out. This is simply not a disclosure the consumer has a right to opt out of.
In this world you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant.