They are amongst the store’s top-spending customers but haven’t ordered anytime recently. They require immediate attention so as to recover them with an intent to transform into strong customers again. Else, they’ll defect pretty soon.
Run a special ‘Defecting Whales Reactivation Campaign’ for this segment. Moreover, you can afford to make the reactivation offer generous enough, as these customers account for larger orders. By recovering them, the store can profit even if the reactivation order is lower than normal.