Outstanding post, OSB.
My personal opinion is this:
Wait for at least a year before panicking about the loss of CCFC, to determine both SISU's true determination to hold onto the club in the face of mounting losses, and whether ACL actually can return a profit. Either a change of ownership, or a profitable ACL might make the need to sell the Ricoh redundant.
If it turns out that ACL are losing money, and SISU are truly determined to hold onto CCFC, then the council should listen to offers to all comers for their share in ACL as a business, and their interest in the Ricoh. If there's an offer that allows them to recover their investment, I'd want them to take it, but the Council should not treat SISU as either a preferential bidder, or refuse to entertain offers from them. The best way to determine the market value of something is to offer it to the market.
If however there isn't an offer that allows them to recover their investment in this way, then the Council should reconsider the site in total - and see whether knocking it all down and developing it as housing and/or commercial makes more sense for the city. The one thing I don't want is for the Council to subsidise CCFC (again) because of the club's continued mismanagement.