not too mention the "terrorist attack" insurance policy that was taken out weeks prior on the buildings that required millions of dollars in maintenance
the best example for comparison is Asbestos. back in the day, there was no "Asbestos exclusion" or any wording in a policy saying they would not cover asbestos. thats because that typa shit wasnt on the radar of carriers. when asbestos started reeking havoc, and thousands upon thousands of claims were filed, carriers were brought down to their knees. Lloyds of London, who have been around for thousands of years, almost crumbled because of asbestos claims. Warren Buffett pretty much saved them. now there is an asbestos exclusion in policies.
same goes for mold. mold was never excluded from policies. now, since the out break of mold related claims, you would have to buy a pollution policy if you wanted to be covered for any mold claims.
they didnt buy "terrorist attack" insurance. in theory, terrorist attack claims would have been covered regardless back then.