I'm certainly not aware of any liveaboards in that area, and the location of the dive sites - all within very short distances from the shore, either of Cozumel or of the Yucatan mainland, and relatively short boat rides (meaning less fuel costs - and fuel is expensive in Mexico) - and the wide availability of facilities on shore, not only lodging like hotels, hostels, B&Bs, rental houses and condos, but also restaurants, means that the traits making liveaboards either necessary or economically viable simply are not present. For those who like the sole focus on diving - dive, eat, dive, eat, dive, sleep, then repeat - that liveaboards offer, you can get that on Cozumel from a shore-based location, with much more comfortable lodgings, much better quality and variety of food, and more economical diving. I doubt very much whether a liveaboard operation could ever make money in the Cozumel-Yucatan area.