Why was FDR said to have "put the fox in charge of the hen house", when he named Joe Kennedy, Sr. to be the first overseer of the SEC?

Back then Successful Stockbrokers made their money from what we call "insider trading" today. the richest had the inside track. Joe Kennedy knew that (after doing that himself) so was seen as the best person to make the rules to prevent it. He was quite successful and many brokers lost money. One of them who almost went broke was John Vernou "Black Jack" Bouvier, father of Jackie, future wife of Jack and the future daughter in law of Joe Kennedy.

Source:
The Kennedys: Dynasty and Disaster - Page 79 - Google Books

pages 78 and 79 of the book at googlebooks can be previewed on this link:

http://tinyurl.com/KennedyDynastyGooglebooks (click on the page number)