Is Senator Liawatha Warren a member of the U.S. government? Yes
Does Amazon sell Senator Warren's own books? Yes
Did Senator Warren, a member of the U.S. government, direct Amazon, a contractor for the U.S. government, to stop selling a third party's book? (on official government letterhead no less) Yes
Senator Liawatha Warren committed a crime, violated the Senate's ethics rules, and also committed a tort against the book author.
I’m a firm believer in schadenfreude. You mentioned Liawatha’s books being sold by Amazon.
A search using Amazon’s own engine immediately brought up a number of casebooks and supplements covering commercial law, law of debtors and creditors, and bankruptcy.
One can only wish ....