Because FOX and their subsidiaries like the “Astroturf” TeaBags, employers of Professional and Amateur Liars on a massive scale, would have somebody within their ranks who would think it a good idea to spring the notion that the recent spate of Oil Well disasters were “rigged” not by the sheer STUPIDITY of the Oil Corporations and their Greedy minions, but are instead a sinister plot by Anarchists and Environmentalists in order to embarrass the Oil Corporations.
Of course they wouldn’t have proof or even Evidence, because their intended audience is really stupid to begin with. And there would be no way to gain any such evidence other than fabricating it, like they fabricated that “Kenyan birth certificate” a few months ago.

Truth would not be on their side so they’ll avoid anything resembling Truth. It’s their way.
It would also run counter to their argument if anybody on their side said this, so I’ll say it:
Those of us in the Environmentalist Left don’t make money from shit like that. The Oil Corporations DO. The Anti-war Left doesn’t make huge profits off Non-War, (although every war that ISN’T fought is a HUGE profit for everybody in the world, including us. Trickle Up economics) And the Oil Corporations, on the other make profits that are the worst kind of Obscenity from every war that IS fought.
Since every good Conspiracy Theory, especially those that involve actual crimes, involves somebody making a profit.