I'm not sure what that has to do with what I said. Automattic make WordPress, Automattic want WP Engine to pay for part of the development cost and are making life difficulty for WP Engine until they do. WP Engines only recourse is to fork WordPress into their own project, but that then means they would have to pay for the development of their fork.
Automattic could decided to take their money and liquidate the business tomorrow, nobody can force them to continue developing WordPress. GPL does not entitle you to continued support from the developer.