No, I don't think so. Buying his debt at discount is one way he could actually avoid technically defaulting. For example (using exaggerated numbers to make the math easier):

1. Suppose pirate has taken 50,000 BTC in direct loans, and 500,000 BTC via passthroughs.
2. Suppose pirate, after paying weekly interest, still has 150,000 BTC in his bitcoin wallet.
3. Suppose pirate pays back the direct loans, leaving him with 100,000 BTC.
3. Suppose the passthrough shares are being sold for 10% of their face value.
4. Suppose pirate buys all the passthrough shares for 50,000 BTC, leaving him with 50,000 BTC.
5. Suppose pirate pays back the passthroughs, 50,000 BTC at a time.
6. The coins pass through, back to pirate, who then pays back the next tranche of 50,000 BTC.
7. Repeat ten times, and pirate has technically not defaulted (although he has screwed those who sold their passthrough shares at 10% of their face value).

Sure, there are a lot of suppositions and extreme figures above. But something like this is not impossible.