Sure, allow me to clarify.
Matt voices a number of grievances including WP Engine's changes to WordPress, their use of the term "WP", their donation/sponsorships, and more. At first glance they all seem a bit silly.
The important context, in my opinion, is that this comes after the breakdown of a licensing agreement between WP Engine and Automattic, an agreement that would've seen tens of millions of dollars paid to Automattic by WP Engine for a license that WP Engine does not think they need.
To put a point on it, none of the things WP Engine is accused of doing were problematic before the breakdown of licensing negotiations or the filing of WP Engine's lawsuit.