Seller can claim it immediately when he sees and accepts the order, but buyer has some protection from ghosting. With cashu, any server (or even the buyer) does not need to be online at the time of purchase.

Imagine you give your waiter a tip or gift someone else some sats via cashu as a present. If you see then after xyz time that they still have not redeedem your gift you can just take them back instead they getting lost/unused. Obviously as soons as they are accepted/reedem you can't get them back. So I guess what @Martti Malmi was saying is e.g. I could send you know now 100k sats in cashu via DM and say please build xyz into damus. And if you don't want or ignore my request I could always get my sats back without having to ask for a refund.