I'm curious where your certainty comes from. I happen to be a (former) lawyer, and my perspective is that it's quite possible that there are loopholes here. If there is a settlement agreement that refers to "income" then it would likely be defined in terms of taxable income, which is a generally agreed upon standard.
You refer to a court considering gifted money to be available to repay the debt. But do we know if there was a private settlement, or something that is being administered by a court? If it's a private settlement, then the court would not be able to step outside the agreement and loop in other property. They would say that Nintendo is a sophisticated party and it should have negotiated a more airtight agreement. But like I said, I don't know if this is a private settlement or something that a court is administering.
If you have access to other facts, or more nuanced reasoning, please do share!