I wouldn't say that there's little reward for Booker. He violated the rules for "transparency" and for "the people", but did it in such a way that he isn't going to be subject to much sanction, as it was a big bag of nothing. If they go after him, he plays the 'persecuted hero' card, along with the 'hero of the people' card. He's going to play this up that he is a 'hero' because he broke the rules to help the 'people'.
Somewhat brilliant strategy to move ahead within the Democrat field, with very little actual blowback possible. Especially for such a moron.