I have very little doubt that CO would honor the ticket if they had issued it. They have pretty consistently in the past. But when a mistake fare is reserved but not issued they haven't and they have no obligation to. Nor would I expect them to. Having a ticket and having a reservation are two different things; always have been.

Maybe I'm wrong and maybe this isn't the mistake deal that I believe it is. But the timing and the OP's description of the problem suggest that it is.