I agree that for many seastars 2 hours is not long enough, depending on the tank age and water parameters. It is imperative to know your specific gravity and other parameters. What is "fine" for fish only systems is often fatal to seastars.
Note that it can take a month for them to die of acclimation shock.
It would also definitely help to figure out what kind of star this is. :notsure: Certain one's are "relatively" more hardy than others. Chocolate chip stars are much "hardier" than any Linckia or Fromia star.
In addition, not all seastars can be spot fed and will die in tanks without sufficient live rock in 6 months to a year.