OK, suppose the OP had bought his business class ticket with cash money, and the exact same thing happened: he ended up in Y for part of his trip. Don't you think that the carrier that sold him the ticket should at least refund the difference between first and economy class fares for that part of the trip?

Miles tickets are no different. The OP ended up in an economy seat, but paid business class miles. The carrier that issued the ticket should refund the difference in miles, whether it was their fault, the operating carrier's fault, or the weather's fault.

If I were the OP, I'd pursue a partial miles refund from CO, and some other sort of compensation for the canceled flight from LH.