Too much complexity.
That law would be one more way to keep 'outsiders' (those NOT in the deep state) from running for office. I understand why people like Graham would like to keep competent people who can accomplish something beyond fund raising and running their mouths from running.
Simpler to change the statutes. Tax privacy is a statutory creation. Tax info was originally public. This caused heartburn for the powers that be, so they got privacy from Congress.