Yea you thought that you helped someone, however the risk is still there on your end. It is a tremendous risk for you. Not only that but the sticky in this section says that any sob story is likely going to be a way for a scammer to get you to send him funds. The 0% interest rate certainly does not help you manage that risk, however the fact that it was a USD pegged loan means that you will end up with more bitcoin assuming he does decide to repay you

Hi, repayment is almost due.

SInce price went down, you only have to pay 0.5BTC.