What is concerning is the fact that a failure in one part of the network was able to spread so wide. yhere are certain words in there that make it sound like they don't capacity plan or anticipate these sorts of failures? Certainly the lack of isolation is not good, but that's pretty common in the mobile carrier space.
It sounded more to me like they had planned, but a failure mode slipped through.
"This redundancy failed us and resulted in an overload situation that was then compounded by other factors" seems like those other factors may have been more important too.