What do you expect if all exchanges delist Luna? Do you want all Luna holders to have no chance to sell them again?
Anyway, those exchanges have no responsibility for the drop in crypto coin prices. They only facilitate people to trade the coins on their platforms. If there is a big drop in Luna price, you should ask Luna founder or the team. They are the ones who have the authority to explain it. But they also have no responsibility for your losses because they never asked you to buy Luna. You bought it with your own intention, didn't you?