I doubt he is using it to get the price down. Most likely Disney simply inserted language in the contract barring any ad skipping technology and Dish may be trying to negotiate some sort of skipping allowed.
The media companies view what Dish is doing as a violation of their existing contracts. They obviously (or they would have barred it) thought they had it covered with language that probably required complete delivery of the programming without cuts. Since the hopper does not alter the programming in any way with their skipping, it gets around the language of the current contracts as shown by the courts not issuing injunctions before trial. A trial will eventually determine if Dish did violate the copyright in some way or another, but for now it looks like ad skipping via the method being used by Dish is not violating the current contract.
I bet every channel's lawyers have been working overtime to put in language to prevent any automatic or provider assisted ad skipping in their contracts. I predict this was a one time loophole used by Dish that will be closed in all contract renewals.
But, this does not preclude a deal where someone pays extra for a channel to compensate for ad skipping if the provider feels they could attract more customers by offering this premium service. Perhaps Dish will use some of the monthly Hopper fee to buy this premium service for their customers.