Pirate asked the PPT operators for their books so he could pay people directly (I think.)
We have no idea why he asked for that information. I think the most likely scenario was that it was simply a stalling tactic. Since no payments were made even for PPT operators who complied, it's unlikely he ever intended to make payments.
So the PPT obligations could now be removed, and 100BTC to buy a PPT is now 200BTC (instead of the 300BTC.) Would this be to pirates advantage?
First, it wouldn't remove those obligations. Pirate's belief to the contrary, if he had one, is mistaken. And it wouldn't be to Pirate's advantage except in the unlikely scenario where you repays a PPT operator, the PPT operator fails to repay the depositor, and that depositor goes after Pirate.
If the PPT operator is honest, the funds are only doubled. The tripling is locked on the books of the PPT operator.
Say I deposit 100 BTC with a PPT operator. I get a 100PPT coupon. The PPT operator deposits the 100 with Pirate. He gets a 100Pirate coupon. Pirate now gets the 100 BTC and circulates it. I have a 100PPT coupon I can circulate. Pirate has 100 BTC he can circulate. But the 100Pirate 'coupon' cannot circulate as the PPT operator must hold it so that he can pay to me any funds he gets from Pirate. In order for my 100PPT coupon to exist, the PPT operator must hold a 100Pirate coupon, so that's locked. It works the same way with banks and dollars and it's why loans double money rather than tripling it.