Sounds to me like Amazon has found a loophole in the law. It agrees to list anything for sale, with no anti competitive conditions, but then only recommends customers buy things that it believes are in the customers best interests.
The FTC will struggle to argue that is illegal. Amazon can't be compelled to recommend stuff. (free speech etc). Also, what they recommend is in the consumers immediate best interests.
It will be hard for the court to argue that amazon should start recommending more expensive items to consumers, just to push consumers into looking for a cheaper platform.