Sounds like nothing more than a calculation provided for the borrowers convince, but actually serves no real purpose. You might look at actually providing a hedge to protect from a rising bitcoin value against fiat for an added fee by buying calls.
Please, read the OP again.
If you borrow 10 bitcoins today, to pay next month, you will theoretically pay aprox. USD $300.
Now suppose that in 10 days the bitcoin price jumps to USD$ 1000.00 per bitcoin, you still need to pay 10 bitcoins back, but now you will need USD$ 10,000.00 to buy 10 bitcoins!