Why doesn’t WP Engine just fork the project? Is an account on Wordpress.org the only way for someone to use WP?
They don't want to pay for all that. They want to make money. That might save Mullenweg in the end, despite himself. He might be ordered to help them set up an alternative plugin directory, but the court probably can't or won't force him to continue doing business with them. Keeping up their mirror of the WP infra might cut into profits too badly. All of the huffing and puffing on their side doesn't change the fact that they're basically parasitic. They do nothing for Mullenweg, and he was doing everything for them.
There could be an outcome where he's about to be forced to pay damages for all of the harassment and help with some complex remedy that still requires them to fork, and instead they come to a settlement beforehand where they (quietly and confidentially) pay him something slightly less than 8% of their revenue and he pays their legal costs and publicly apologizes.