It seems not a good return, 100 coins to make 0.2 coins per day... if you use those coins to buy miners, only 40 coins could make you 0.2 coins per day
But those 40 BTC are then gone, and may never see ROI let alone any profit. The 100BTC (if he's a holder anyway) are better working for him than sitting in some dumb safe wallet.
Don't forget lending is not risk free like keeping coins in the safe. If market moves a lot there might not be enough depth to cover all margin calls, and you might loose $. There's also the risk of exchange going belly up and you loose ALL your coins, like MtGox BitFloor etc....