The species is rarely brought up alive in the first place, and as far as we know is fairly uncommon. Trying to even get one above the surface successfully would inevitably result in a lot of casualties. Their habitat is difficult to replicate properly, especially for an animal the size of a coelacanth. The aquariums that have kept deepwater animals successfully are well out of their range, meaning extra risk of prolonged transport. Not to mention we know next to nothing of their life habits.
It's just not worth the amount of coelacanths that would die when trying to get even one on display.