The letter alleged that "your blatant and widespread unlicensed use of our Client's trademarks has infringed our Client's rights and confused consumers into believing, falsely, that WP Engine is authorized, endorsed, or sponsored by, or otherwise affiliated or associated with, our Client."
If the trademark is indeed on the wordpress.org foundation and not the wordpress.com company, I didn't think that's a fair argument.
When I think Wordpress I think the software, not their hosting or company. Such an argument would only work if the exclusive trademark licensing were actually exclusively used, and not in addition to the very vast Wordpress [software] ecosystem.
WPEngine using the Wordpress trademark makes me think they're using Wordpress. Not that they are affiliated with Wordpress.com (or automattic that runs it).
Their about us pages:
I don't think either is a cancer to the FOSS Wordpress ecosystem. Both seem to give back.