It must have been one helluva pothole ! ! ! I'd be upset as well. You obviously finished the race without incident which frankly amazes me. I'm guessing that there's a tube that is inset in the matrix to accept the headset cups and that is spreading out the actual pressures.
If that is the case I could see where the frame could be repaired but I'd only go with that option if Specialized balks at replacing it.
To do a repair AND assuming that there's a tube that is inset in the head of the frame I'd look at wrapping the whole top area just up to the headset race with multiple turns of carbon tow fiber saturated in a good grade of laminating epoxy. Ideally the same epoxy used in the making of the frame. Carbon tow is a unidirectional bundle of loose fiber strands as opposed to a woven cord. What it would form would be a composite band similar in funtion to the idea of the mechanical band mentioned above but without the risk of point loading the carbon matrix. It would be a permanent part of the frame that would support and fill the cracked area. If you go with such an option it would be a case of using it on short light rides at first with frequent inspections to check for damage or head tube delaminating (any apparent looseness in the "headset" would be a sign of this potential issue) at first. Then as you learn that you can trust the frame the rides could become longer and longer but with the same frequent inspections. It would definelty be a case of slowly coming to a level of trust with it. AND NO MORE GIANT POTHOLES ! ! !
