That is what they did, their actual current advertising includes: "The most trusted WordPress platform", "The Most Trusted WordPress Tech Company", "[WordPress's] #1 managed provider", "WP Engine is the #1 platform for WordPress". They also have service plans on offer explicitly branded by them Core WordPress, Essential WordPress and Enterprise WordPress.
If they are "The most trusted WordPress platform", that implies there is more than one platform. That implies that none of them are first party WordPress. So I don't buy that.
(Regarding their plans, I think they would be safer to put the word 'Plan' at the end of their plan names.)
I know what you mean but if CNET Downloads advertised themselves as “The Most Trusted Source for Firefox” The Mozilla Foundation/Corporation would not allow this. A consumer new to the term WordPress might be given the impression that wpengine.com is a more trusted platform/source for the software than wordpress.org itself.
