Would you want a compensation if Warmane would be shut down completely, for example, by Blizzard? The realm is being shut down, they are thinking of some sort of system for transfers.
Coins were a gift from Warmane, just as your money was a donation to Warmane. Private servers and their realms tend to be closed, deal with it. As mentioned, there will be some sort of transfer system available for you, which is being worked on.
(I'm not saying they won't refund coins as I'm not member of staff, I'm saying that it is their choice and freedom to give them back or not, they are not obliged to do so morally or by law.)