AND that's the thing about "not letting anyone else use it" -- you have to protect the trademark of that asset, or else it can eventually be considered in the public domain. This is part of the reason why some companies seem to come down hard with cease-and-desist letters on kids and grannies with even small things that don't otherwise materially hurt the business. If they don't protect their trademark, they may eventually lose it.

But yeah, they bought it, and apparently the contract language doesn't tell them they can get out of the royalties by retiring the asset.