I don’t think there was a clear discussion of the terms of the deposit. What he is asking is what is the usual common sense protocol.
Need more info, did you have contact in those 3 weeks, did you tell him you were selling it and give him a last chance? Seems like 3 weeks is a pretty long time to leave a deal hanging but you did sell it for your full asking price so it’s not like you missed out on a seller. You did miss out on another deal with an engine but I think it’s a stretch to hang that on him.
Might be worth $100 to get the guy off your back and lesson learned, next time set a time limit.
Gif