Sounds similar to Nintendo dmca takedowns. You could challenge the defamation claim in court and win, but you would have to spend a lot of money and time, and the only thing you get back in the end is the right to post the review.
You could challenge the *DCMA* claim in court and win, but you would have to spend a lot of money and time, and the only thing you get back in the end is the right to post the *code to Github*.
