After reading your initial post, the good samaritan side of me kicked in, I would had returned the money assuming I didn't see the other side of the story which comes as a surprise. Thought the exchange was decentralized, how then were they able to seize or empty the account of the user?. I'll be glad if more details are reviewed like the exchange name so we can stay away from patronizing them in the future. They made an honest mistake that they can take to social media and ask for their funds to be returned.

Probably the receiver would see this new development and do the needful, which might benefit him more as the whole world will see his good deed and probably reward him more either directly from the exchange or other source. Although if at last the receiver refuse to send back the fund I won't judge him because if I was in his situation, I'll likely do the same or take back my funds and send back theirs.