Tell that to the guy who got upset with WP Engine. EmDash is clearly "inspired" by WordPress including in its UI, so there's definitely something to it.
The phrase "spiritual successor to WordPress" is not likely to be judged a trademark violation, though. It doesn't create confusion in the marketplace as to whether Emdash is WordPress.
The problem with WP Engine was that the name is confusing to users who aren't familiar with it. Presumably the WordPress Engine is the core of Wordpress? Or it's the thing powering Wordpress? It's easy to see ways in which an end user could be confused which was which.
Conversely, this product is called something else, and while their blog post references Wordpress repeatedly it's in a way as to make it very clear that this is not that.
That situation had nothing to do with reality either. It was just some guy being upset at someone and starting a war all of the sudden. War it lost anyway.
Matt got upset because they forked his open source project and built a hundred million dollar revenue business on top of it without contributing anything back to WordPress.
He'd have more of a leg to stand on if WordPress wasn't itself a fork of an open source project.
Matt should have built something open core or fair source licensed - free for customers, but stops competitors from stealing your lunch. He has no legal ground to argue his case now.
It's a much bigger deal with hyperscalers poaching and stealing, like AWS and GCP ripping off and stealing most of the revenue from Redis and Elasticsearch. That's dishonest and evil in my mind.
Totally orthogonal to this issue of marketing comparisons.
WPE never forked a thing. They were a successful company after he backed out of an investment with them, he resented the success, blackmailed them for 8% of their top-line revenue, then threw a tantrum when they told him to pound sand.
