It sounds like PayPal isn't actually buying Bitcoin, but instead created their own proxy bookkeeping instrument. Speculation, but that's what it sounds like to me if you can't have Bitcoin's utility and only its store/speculation.
That sounds extremely risky for PayPal. They're effectively shorting bitcoin by doing that. If the price rises dramatically they have to just come up with that money out of their own coffers. If they buy bitcoin they can merely liquidate it and pay you the proceeds when you sell your paypalcoins.
