Lots of respect to Oanda for doing this
They prob had opposite positions in their market making book and are willing to "spread the wealth" to get customer market share. Odds are they won't do it again and it also means that your capital is at a firm more like MF global than Charles Schwab.
Maximum Losses. OANDA warrants and represents that the fxTrade System has been designed so that your total aggregate Realized Loss can never exceed the sum of the total aggregate deposits made to your Account and your total aggregate Realized Profit.
account equity can fall below margin requirements at the time orders are filled, even to the point where account equity becomes negative. This is especially true during market gaps or volatile periods. FXCM will not hold traders responsible for deficit balances in this scenario, but clients should be cognizant that all funds on deposit in an account are subject to loss.
[...]However, it should be noted that FxPro operates on a 'negative balance protection' basis; this means that the client cannot lose more than his/her initial investment.
Still doesn't add up. If you're paying out those who were long CHF, but forgiving those who were short it...