It is not obvious that this action is actually in the best interest of open source. It's obvious that it's in the best interest of Elastic, but there is nothing intrinsically special about them that means they are the best stewards for the code until the end of time itself versus Amazon or anyone else for that matter.

The ability to fork in open source is a feature not a bug and ultimately the community of users and developers of these projects will decide what works best for them. In this case it isn't even a fork, it's new plugins that the community can consume under a FOSS license.