If I pay some of my bills but don't pay the others then I'm in default, no technicality about it.
Two thirds of the federal budget is non-discretionary, legislatively mandated spending. Interest on debt, believe it or not, is not in that category. The roughly $144 billion in Medicare and Social Security payments for the month will have to be paid before debt or military salaries or veteran pensions or any other defense spending. So even if your definition is correct, that doesn't mean that the money will be available to pay it.
I see your point. Moreover, the Clown has run us into a worse situation by his petulance.
Nevertheless, the technical chance of default is only dependent upon his refusal to pay that interest.
I don’t know where you got the $144B figure, but assuming that is correct, it still is less, I believe, than the monthly income to the federal government via payroll taxes and other fees sent through withholding.