From the article:
It’s unclear what comprises the $75,000 Psystar owes Apple.
And we cannot forget that Psystar claimed that they had no receipts from Apple. If they bought a bunch of Leopard copies, why is this called debt? They were bought and paid for. Maybe its credit card debt, but no matter how you look at it, Apple would have been paid as they bought the Leo copies. How else could they have gotten Leopard.
This sounds more like either them buying some Macs or legal debt.