No, it means that Amazon reached the point of considering other solutions than Oracle (I bet partially because of cost) at the time when this project started to

No, it means that Amazon reached the point of considering other solutions than Oracle (I bet partially because of cost) at the time when this project started to move their database workloads that at the time were residing on Oracle to something else. Amazon uses many software vendors, they by no mean suffer from the NIH (not invented here) plague.