Saying "tax revenue is spent on..." is misleading. Taxes are used to take currency out of circulation (roughly speaking, destroy the currency). A financially sovereign state can issue however much money it wants, i.e. it can form whatever budgets it wants. Money is not a limited resource for them. The fact that it will not want arbitrary budgets is a different manner.

They’re not talking about inflation.

I covered a more broad case than inflation, but if they were not talking about it, then their comment makes no sense.