I mean if a business if built on top of your business, is it actually illegal to say "Pay me if you want continued access?" Is it the wording that makes it illegal?
... to the open source project WordPress? 1) it'd be hard to forbid any one entity from using it, based on the licensing, and 2) the announcements and banners pushed to users referenced WP.com, Matt's for-profit competitor which WPengine doesn't use, and brings about elements of tortious interference.