They were using the trademark on the website to describe WordPress the software project under nomitative fair use in the same way many, many hosting providers have been doing for decades. He openly admitted in online comments to trying (and failing) to extort their CEO in private to give Automattic huge payments, and if they declined that he'd destroy their valuation by cutting off their access and buy them for pennies on the dollar. Among other threats leading up to the lawsuit, which taken together made it look like a blatantly selective punitive measure for cynical reasons.

It doesn't help that the word "Wordpress" is used for all sorts of different, but overlapping things: wordpress.com for his private WordPress commercial host competing with WPEngine, wordpress.org for the WordPress Foundation he also controls, WordPress describing the open source GPL licensed project.

Google makes things much simpler to avoid misusing their trademarks by splitting Chrome for their commercial product and Chromium for the open source project.