You could even say “providing all necessary services to cover two runways may have reduced the delays significantly today.” I believe that may have been the case.
Then again, how often would this scenario occur vs the cost? And would you really build a third runway and triplicate the services, purely for emergencies?
It’s a little like the risk of snow, what is the tradeoff between cost of equipment/maintenance/staff training and closing the airport? This is a typical aleotary risk scenario, where the unpredictably of the event makes a probability based response inappropriate and the only realistic option is to add contingency to the operating budget. When the accountants have value engineered the scenarios, it is difficult to justify.
I cannot be absolutely sure, but I would be very surprised if anyone would sign off a business case for such a contingency. By all means argue for a third runway for other reasons, though.