Borrowing to pay for welfare is one problem, borrowing to smooth out fluctuations in production is another. If the robots are to be efficient, they'll produce exactly what is demanded for equilibrium, but the economy cannot be in equilibrium, because people's demands are constantly changing. If for example, there's a revolutionary new product, suddenly the factories tooled to produce the old product need to be converted to make the new product. So, either the people must suffer shortages in supply, or the robots borrow to expand, meet demand, and then pay back the borrowed capacity.

And in fact, if you arrange things right, the robots who have the product that is no longer in demand can lend their unused capacity to robots making a product that is in higher demand.

My point is, borrowing from the future isn't always wrong, it depends on the context. If Western civilization had never invented banking or finance, we would have been far worse off.