Back to the point in hand
Oracle et all challenged the original award as they knew they could not provide the entire contract and the "legacy systems" being replaced were mostly theres
their suit was frivolous.
There are only 3 firms that might have been able to provide the entire contract: AWS, Azure and GCP
GCP didnt really have the capability, Microsoft pulled out of the process first time around, that left AWS to win it.
Trump then got involved, then all of a sudden MS were winning a contract they gave up on...