Your proposed tactic is divisive. How that division will work is a marketing question, and, possibly, a legal question. I know it's a stretch, but people file suits for anything nowadays.......could such a business tactic provide the footing for such a suit?
Eleph-Rhino.
Personally, as an American, I like it! I believe that you would have instant recognition, publicity, and a corps of willing customers if you used such a saying. Who was it that said there's no such thing as bad publicity?
This is the problem. As far as a suit goes, I believe it would be thrown out of court. It could be a media problem that could actually improve my customer base in the long run. It could be that its not worth the risk.
How could it? Normy & Company do speak English. It's a simple, declarative statement. It's like saying "We drink coffee" or "We use pencils".
It doesn't say, or even imply: "We will only speak English", or "We can only speak English", or "We refuse to speak anything but English."
But,alas, you are right: people will file suits for anything nowadays.