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.
Also, do you think that's better for Pirate than this scenario in which he sells:
1. Suppose Pirate has taken 50,000 BTC in direct loans, and 200,000 BTC via passthroughs but also holds 300,000 in passthroughs himself. (These are almost totally free for him to buy, the money just flows back to him.)
2. Suppose Pirate, after paying weekly interest still has 150,000 BTC in his wallet.
3. Suppose pirate doesn't pay back the direct loans, leaving him with 150,000 BTC. But he also sells 50,000 worth of direct loans that don't actually exist at 50% of face value, netting him an additional 25,000 BTC.
4. Suppose Pirate sells all his passthrough shares himself at 50% of face value, netting an additional 150,000 BTC for him.
5. Suppose Pirate doesn't pay back anything.
6. Pirate now has 150,000 + 25,000 + 150,000 = 325,000 BTC.
7. Pirate has technically defaulted, but he also has a *lot* more money than in your scenario.
In your scenario, Pirate winds up with about 50,000 BTC. In mine, he winds up with 325,000 BTC. And we both start with him in the same position (except in my scenario, he has been buying his own pass throughs for awhile now, which is certainly possible). My number for the discount on Pirate debt is more realistic than yours (50% versus 90%). It's definitely in Pirate's interest to *sell* Pirate obligations.