That gets into a pretty.sticky situation real quick.
The fundamental question is: is the non profit going outside the boundary of its status?
I’m not fully convinced that’s the case even in the context of the for profit disagreements with its competitor.
If Automattic is an infrastructure vendor (in a technical sense at least) to WordPress.org, it’s still reasonable that Automattic doesn’t want to just give its competitors free infrastructure.
I own a hosting business that’s heavily built upon WordPress and even I — at a scale immensely smaller than WP Engine - CDN some of my critical plugins and themes myself. (For a lot of reasons.)
WP Engine is absolutely massive. The load they put on systems that they consume from isn’t trivial. Asking for remuneration from a competitor that is using your services, according to their means, isn’t anticompetitive.