No, the operational costs that the paper mentions are only in the millions. (And if we consider the daily total mining rewards, we also see that the price is measured in the millions.) So by far the largest part of the price of a 51% attack will be due to acquiring the ASICs (and/or compensating bribed miners for their ASICs).
Fair enough! I read/misunderstood your previous post as stating that $6-20 billion is
all it takes, ignoring costs for the ongoing operation. But you're right, compared to the initial cost the operational costs are almost neglible.