Football can certainly be homophobic - but does it have to be? There are plenty of lesbians and gay men who love sports, are football fans and will be watching the Superbowl. I don't know that this will do any good, but you can contact CBS corporate and demand an explanation for this.
51 West 52nd Street
New York, NY 10019
Or use this form to wrote them
If you receive a response, and it's that CBS had problems verifying the company's credit status, that's likely bullshit, since the company says it offered to pay cash.
Here is the YouTube video of the ad from ManCrunch.com, the group whose ad was rejected: