I can't go into detail about how I know that, but I know. I'm not saying they won't. The pressure to cooperate is fairly intense. But, so far, they have remained at arm's length from this whole mess and have publicly declared they have not cooperated in the matter to which you refer.
Caveat: No communications provider in the US has been willing to resist federal warrants for information. That is, active investigation for which a clear, legal warrant was provided have induced all of these companies, including Cox, to turn over information.
Also note that backbone providers have pretty much all been implicated as cooperating, which makes much of this moot. If you can "spy" on the backbone, you don't need the downstream providers except as convenience.
Here's a link to a news story about it that mentions Cox:
http://news.com.com/Some+companies+helped+the+NSA,+but+who/2100-1028_3-6035305.html