Having long ago watched while an aircraft carrier flight and hangar decks had to be "respotted" for a down a/c, a complex evolution involving many and no little planning, I don't put much credit in your conspiracy theory (or most others for at matter). Can you imagine the complexity of "respotting" an entire fleet of a/c to accommodate a down bird sitting not where it was supposed to fly, but back where it was supposed to have long departed?

The complexities of moving a/c around to fill a hole are much greater than any savings from a cancellation. Even at DFW, AA's hub, spare a/c are fewer than hen's teeth, and even when available, often the wrong bird to be hurled into the breach (although I've seen an old MD80 or two serve as "Forlorn Hope", when there were no other alternatives and over water not required)