TWC isn't going to cut off the Sinclair networks until they are TOLD to cut them off, or until they are cut off.
Some of the channels are fiber only, regardless if OTA is available. It's all how it is negociated as to what the connections are. So yes, in many cases it is about "cutting the fiber." I'm not sure why you chose the point to argue, and then ignore the whole point that TWC isn't the one that is going to turn this off. They have no reason to. As long as the channel is getting to them and being rebroadcast, their customers are happy.
As soon as Sinclair turns off the feeds to them, or tells TWC to stop, then TWC's customers are unhappy.
So like I said, TWC has no incentive to turn this off. Yet Sinclair is running banners on their channels saying that TWC is going to cut them off.