The obligations are not owed to the Dutch, and I find extremely unlikely that the tax treaty includes language which says "the fee for renouncing citizenship, if unpaid, shall be paid to the Dutch". In the outlined scenario, no taxes are owed. What is not paid is the fee for renoucning, and what has not been done is filing the paperwork. So the question is whether the tax treaty covers this, and whether or not a Dutch court would try to act on behalf of the US government regarding these matters.