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.

Matt seemed pretty fine with the name for at least 14 years, including investing in them at one point.