Even if the show is cancelled? It just doesn't make any sense. Once a show is cancelled, the contract is void.

The contracts aren't with the network though, they are with the studio. And the studio shopped the show immediately and secured another network within one month. There is some sort of contingency where if a show isn't going to be picked up, the studio has a certain amount of time that they can hold their actors under contract, but hardly any time has passed.