I doubt they explicitly said "I'll run without huge pages, which is an important AWS configuration". They probably just forgot a step. And "someone at Amazon" describes a lot of people; multiply your mental probability tables accordingly.

The number of people at Amazon is pretty much irrelevant; the org is going to ensure that someone is keeping an eye on kernel performance, but also that the work isn’t duplicative.

Surely they would be testing the configuration(s) that they use in production? They’re not running RDS without hugepages turned on, right?