This is also my thought, If he borrowed 0.05 he should return 0.05, but we should also give him a limit such as "should be only 1 week" or else he would have added interest so that we will not lose if its value falls.
I saw it too in the Market place and the value didn't matter to them even when it dropped, Because they want to increase their BTC and not the value, Maybe they are longterm holders.
Those lending bitcoin are definitely long term holders since for what I can see they always ask for the the loan to be repaid in bitcoin, and while I wish them well we must recognize how risky it is what they are doing, we are living in an economy based on debt and it is difficult to understand how an economy based on bitcoin could work without it but for a very long period of history only those with lots of resources, reputation and a productive idea or business could get access to loans.
We live in a very particular age in which everything can be purchased with debt even food and I think it will not last long as we are reaching the limits of what an economy based on debt can achieve.