You wrote [bold emphasis mine]:
It was reported that
NASA managers have said the system is rated for two more rollbacks to the VAB, so after this hurricane decision it appears the stack will need to launch after its return to the launch pad.
The key word here is "rated". What that means is that NASA's engineers and safety officers, Boeing's engineers and safety officers, Northrop Grumman's engineers and safety officers, ULA's engineers and safety officers, Aerojet Rocketdyne's engineers and safety officers, Lockheed Martin's engineers and safety officers, Airbus's engineers and safety officers, as well as the engineers and safety officers from all the other contractors, involved space agencies, the Eastern Range, etc., when they made their safety checks many years ago, thought it would be enough to run their risk calculations for 5 rollouts.
So, for now, all that this means is that after 5 rollouts, they need to run their calculations and assessments again, need to inspect the vehicle(s) to check what the actual status of the wear and tear is compared to the worst case assumptions they based their earlier assessment on, and write a new report.
It is highly likely that the result of this report will be that they extend the rating to a couple of more rollouts, simply because it is very unlikely that every single one of the previous rollouts met the worst-case criteria that they used in their calculations. In fact, it is highly likely that even in worst-case conditions, the stack can support more than 5 rollouts, however, they didn't bother to run the numbers because they didn't think they need it.
You can imagine that they calculated 5 rollouts through a hailstorm during an earthquake with the crawler breaking down halfway or something like that. (Note that I completely made those conditions up, but conceptually, that is how risk assessments work.) Since none of those things happened during the rollouts and rollbacks, it stands to reason that the stresses on the stack were much lower than assumed, and thus additional rollouts can be performed.
Here are just a couple of other examples where the actual performance of a vehicle, engine, or spacecraft far exceeded the rated performance:
- The Falcon 9 booster was designed for "at least ten" reflights with minimal refurbishment. The fleet leader now has flown 14 times.
- The Sojourner Mars rover was rated for a week to a month, but ended up operating for almost three months.
- The Spirit and Opportunity Mars rovers were rated for 90 days, but ended up operating for 6 and 14 years.
- The Curiosity Mars rover is rated for two years, but has been operating for over 10 years now and is still going strong.
- The Ingenuity Mars helicopter is rated for 3–5 flights and 30–45 days and to not survive the winter, but has been operating for 32 flights and well over 500 days and is still going strong.