Difficult decision. They are a lot of work and time in an aquarium and the tidal pool takes care of all the maintenance tasks and expenses but you already have the tank and a maintenance routine. Raising one from tiny would mean not being able to release it back to the wild to breed I would think since it would not have learned to protect itself or find food but fortunately, this species is extremely common and exists in healthy numbers. You already have some idea of life span in situ since you mentioned that a photo review showed roughly 2 years before they disappeared. The ability to observe the difference between one in an aquarium and similarly aged ones in the wild would be too tempting for me to avoid though (in addition to the fact that they can make terrific pets).