Well, it does have the limitation of ticking off most of their (hearing) customers who might not come back to spend money. They are likely afraid of losing business, so they are not going to open caption if it means that hearing people don't come back.
This sort of argument doesn't really hold water if they have never done it in the past. Can you think of any theatres where all of the movies were open captioned in all showings? Did they ever do this? They cannot use this argument if it they haven't conducted a study to find the results.
Besides, you know what's ironic about the argument? The fact that the majority of closed captioning users are hearing. Just go in any sports bars, you'll see that a lot of their TVs are closed captioned, it's the same with gyms. You don't see people throwing a fit over a football game being closed captioned.