The problem is that if Goat buys back bonds, he still has the Pirate deposits that were backing them. If pirate pays out later, it will be impossible to pass-through those payouts to the bondholders. This would not be acting as a true pass-through. The pass-through operator should just be moving money from A to B, and buying back some bonds at a discount would be causing a distortion.
Not at all. He just pays through precisely the same way and winds up paying some of the money to himself. It is no different from anyone else buying the bonds -- it just happens to be him. (Again, assuming he doesn't leverage information he gained as the operator. By the way, if it were me, and I had any good reason to believe a payout was imminent, I would freeze bond transfers to protect bond holders from others who might get word early.)
Think about this: Imagine the Greek govt used their current funds to buy back their own bonds for pennies on the dollar. They would have much less debt outstanding, right?
This is a breach of their bond contract because as the issuer of a bond you (and only you!) are obligated to pay back bonds at face value, and using funds to buy back at a discount is an improper use of available funds.
Now, if you are saying that if Goat makes a distinction between his personal speculation on GLBSE and Tygrr operations, we run into the whole insider trading debate. Should the CEO of a company be allowed to short the company's shares in his own e-trade account? No. Shareholders should demand that their CEO does not create conflicts of interest via his personal trading/security positions.