Aetna is a private company. They have every right to use legal tactics in their negotiations to further their profits and help their customers. As long as the company is being honest about their statistics, I don't think that they are doing anything wrong. Government needs to stop being so involved in private businesses.
It's only fair to allow private companies to use government involvement in projects as a bargaining chip, because Obamacare and the U.S. Government has interjected itself into private business. It would be unfair if the U.S. Government could make regulations that govern these companies if the companies can't act in their best interests based on those regulations.
This is an unfair and immoral practice. Unfortunately there is no way to regulate this or to create a law that would not (at the very least) cause unnessary legislation and paperwork, and at the worst would make some fair buisiness practices no longer legal. THis is unique situation and should be treated as such.
The financial story of Aetna depicts a manipulation of their involvement with the government. When Aetna was denied their merger with Humana, there was a threat to pull out of the Obamacare system. This tactic shows a priority of the company goals over the welfare of the U.S citizens. The profit motive is clearly the goal of Aetna.