Interest rates are extremely low right now, most banks barely offer 1% PA on fixed-term deposits.
To put in perspective, and with the best case scenario, the interest that BFL would collect from a bank just about pays a descent salary for only one of their employees. The smartest move would have been to convert the funds back to Bitcoin after BitPay converted the funds to dollars which were deposited into there bank. If this were the case, there would be no way for them to lose money or face if a meltdown occurred. In the case of a meltdown, they could easily show that all the funds are sitting in a Bitcoin wallet(s) readied to be returned like a swarm of locust. Even if the exchange rate falls drastically, it's a face saver, albeit investors (for lack of better word) would receive less dollar value back, they would see integrity, of sorts, knowing that BFL tried.
(pardon me if I got my tenses mixed up in the above, but hope you got the gist)
