No the executive has to follow LEGAL law.
The legislature is not free to write just whatever law it wants. The legislature is not free to violate the separation of powers inherent in the structure of the US government. It is not legal for the legislature to pass unconstitutional laws.
This is fundamental to the design of the US government, and for a very very good reasons.
And so the executive is legally, constitutionally, required to pay the debts of the United States regardless of what the legislative branch may say.