Users are confused as to whether or not paying for a license for ACF Pro (a highly popular custom forms plugin for Wordpress, published by WP Engine) constitutes as being "economically related to WP Engine" and might impact their agreements with Wordpress.org
In response to this confusion, Matt Mullenweg told those users to consult an attorney. Unfortunately for most users, consulting an attorney before agreeing to login to a website is not a financially viable option.