What would the point of that be? If they were to operate a ponzi scheme then they would just take funds from customers to buy the hashlets to payout the mining revenue, there would be no need to buy actual mining equipment. Also the 5 PHs represents the additional mining capacity they are purchasing, not their existing capacity (5 PHs is ~1.8% of the total network).
In regards to the controversy over their new altcoin, I don't see why people can't wait a little while to see who exactly will accept it as payment.
The point would be to spend a little money to make a lot more money.
Shit, Pirate put 5,000 coins in escrow on a bet that he wasn't running a ponzi. That publicity made him so much money that he probably didn't give a shit when that bet got paid out.