I'm responsible for the site's well-being and putting up that latest notice, let me explain without having to resort to questionable mental gymnastics like you did there.
As Chris already mentioned, this site is a hobby. There's no money to be made. Not for me, not for any owner and not for the moderators. We're doing this for fun in our free time. Our team consists of members who, mostly, speak English as their native language. We used to have Spanish speaking moderators, too, but they've left the site a while ago and we didn't really feel the need to fill that specific spot since.
I value the time my moderators invest to keep the place as tidy and welcoming as possible. Unfortunately, due to an influx of Spanish and Portuguese speaking users over the last few years, there's also been a stark influx of Spanish/Portuguese posts being made which originally gave birth to our "No English?" sub in the Editing forum to cater as many people from all around the globe as possible. While we still think it's a great idea, that, unfortunately, didn't decrease the number of posts being made in a foreign language outside of that sub. Us having to resort to translators not only became annoying and time consuming, it also lead to me putting up several notices in big yellow boxes pretty regularly, asking people to please refrain from posting in any other language than English. Seeing you being a member since 2012, I'm honestly baffled by how you simply couldn't connect the obvious dots prior to creating this thread: Those notices didn't work, people didn't care when they've dismissed that yellow box. And if people don't feel the need to have at least an ounce of respect for those running and managing this site by obeying that one simple rule, then it's time for us to stop having respect as well. Is it harsh? Sure is. But it's the only thing that, so far, seems to be working.