I would have thought that we had a contractual obligation to CP to display the CP logo on our shorts. If the HN group decide to shut down CP that is a business decision they make and must consider the consequences. This business decision does not change our obligation to display the CP logo. Obviously, exposing a defunct brand is of little value to the HN group. Accordingly, HN would seek to negotiate with contractors to CP to allow HN to step into the rights of CP. Given the relative worth of the HN brand vs the CP brand (it's a much more recognised brandname and logo), I would seek to recover additional sponsorship from HN in the negotiation to agree to the change in logo. I would argue that HN would generally pay more to have the HN brand and logo advertised than the CP brand and this is just a reflection of the relative market values of the respective brands.
I would argue using your logic then HN could have just pulled the pin and walked away from the contract which they haven't done, they are honouring a contract that their company via one of it's samller companies had with the RFC
HN owned CP, therefore by extension our contract with CP is in fact with HN (acct & corp law 101 = control is control is control) the contract remains the same just a change in the name on the shorts with added bonuses to RFC members with the availability of more discounts available at HN stores on a greater range of goods eg bedding, carpets etc other than just electrical applainces.