Hat tip to Michael J.W. Stickings, who points out that, despite the stated reason,
“This ad does not comply with our clearance guidelines because it unnecessarily singles out an individual company and person.”
they are most likely refusing to air the ad because Big Insurance and Big Pharma spend beaucoups bucks on advertising -- and CNN won't allow anything to hurt their bottom line.
Even the needless deaths of thousands of people.
Also, it's not too late to contact your Congressvermins (Representative and Senators) and let them know how you feel about the state of health care in the US.
The wingnut sheep have been reduced to trying to shout down legislators, so well-reasoned phone calls, faxes, and emails will likely be even more productive than usual.