From the fact that different parts of the website can go down at different times, the app can work when the website doesn't and vice versa, I would say their systems are probably pretty siloed so yea, one restaurant launch failed and brought the website down for a bit but it didn't stop business completely, phone reservations were still working.
That was not an AWS problem, that was a Microsoft security update problem, nothing to do with storage, and I remember it quite well since DH is now in the Healthcare sector and it was all hands on deck to make sure systems could work so patients didn't die. Honestly even though every company seems to be pushing to go to the cloud I would be a little surprised if Disney did since it costs more to do that, the upside is you only pay for what you use instead of having redundant storage space just incase and it's on AWS to fix things when they break. The truth is most big companies develop their own products/apps/systems in house because they have very specific needs and quite a lot of that has to be locally stored, AWS is good for a lot of things but it is not a catch all (which is what DH has to explain to directors and VPs quite often).