Clicking through to the AWS blog article [1] we find this:
> At AWS, we believe that maintainers of an open source project have a responsibility to ensure that the primary open source distribution remains open and free of proprietary code so that the community can build on the project freely, and the distribution does not advantage any one company over another. This was part of the promise the maintainer made when they gained developers’ trust to adopt the software.
I have enormous respect for Adrian's work on cloud systems but the quote above seems very self-serving for Amazon.
Open source is bound by licenses that define the terms of open source code use. There's nothing whatsoever in the licenses that binds the project developers to continue to work on the project, to maintain similar license terms in later releases, or to take (or not take) any other action in their lives. To argue otherwise seems contrary to the notions of freedom that are the foundation of open source software.
[1] https://aws.amazon.com/blogs/opensource/keeping-open-source-...
Edit: typo corrected