>But they explicitly say, and have for years, that “WP” can be used by anyone for any purpose.

>You can’t turn around and try to enforce that.

I'm not sure what you mean. WordPress is quite clearly turning around and trying to enforce that.

It's a shakedown, the whole point is to force WP Engine back into licensing talks. A bulletproof legal foundation isn't necessary, just a legitimate complaint that can force WP Engine into court.