One storyline is that they're using it as leverage since the administration intends to block their acquisition of Humana on anti-compe ive grounds.
U.S. judge finds that Aetna misled the public about its reasons for quitting Obamacare
http://www.latimes.com/business/hilt...123-story.html

Aetna claimed this summer that it was pulling out of all but four of the 15 states where it was providing Obamacare individual insurance because of a business decision — it was simply losing too much money on the Obamacare exchanges.

Now a federal judge has ruled that that was a rank falsehood. In fact, says Judge John D. Bates, Aetna made its decision at least partially in response to a federal an rust lawsuit blocking its proposed $37-billion merger with Humana. Aetna threatened federal officials with the pullout before the lawsuit was filed, and followed through on its threat once it was filed. Bates made the observations in the course of a ruling he issued Monday blocking the merger.