That quote is blind patriotism and it's toxic. There's nothing wrong with speaking multiple languages, being proud of your home country, or practicing the culture of that place. No one is any less American for doing those things. I'm all for assimilation and I think everyone who comes into a new country should do their best to assimilate, but if they want to hold on to a piece of their original culture, or their original language, they can do that and it doesn't make them any less American. In my book, if you're an American, you're an American. End of story.