My bet is...

... Beck will interpret this as an infringement of his First Amendment right to Free Speech:

GEICO Pulls Its Ads from Glenn Beck Show

But he'll be wrong (what a surprise!).

The First Amendment guarantees (among other things):

Congress shall make no law... abridging the freedom of speech, or of the press

The Amendment - the first of our Bill of Rights - prohibits the government from restricting our speech.

It doesn't promise that the free market must pay for our speech.
If nothing else, I'd willing to bet that Beck is a big believer in the free market!