Did I misunderstand something about the scenario here?
Wordpress foundation is a non-profit that develops and hosts installation packages and updates.
WPengine is a for-profit company that sells wordpress hosting.
All WPengine installations constantly look for updates and download these from the wordpress foundation. I'd bet they probably rack up half of their bandwidth costs.
WPengine can of course freely use wordpress' GPLv2 licensed stuff, but it sounds like their leeching of resources was the main pain point.
To either contribute or host their own installation packages sounds like a fair request at the scale WPengine has been operating.
Hetzner, for comparison, sells virtual private servers running Debian. Debian is free, under a similar license as wordpress. Hetzner is a Debian partner and coughs up dough. Hetzner hosts their own mirrors to reduce load on Debian's repositories.
Be like hetzner. Stroke the hand that feeds, or are least don't tug at it.