What language someone speaks in private is there business I fact I would encourage this around a family children so they become fluent is both languages.
However what language someone speaks in public is different if someone is fluent in both.
It can be rude to speak at length in a foreign language in front of a non speaker.
It is a way of talking behind someone back in front of someones face.
I know many non Hispanic that speak fluent Spanish and you would be amazed at what is said in front of you and about you when its assumed you dont understand
And you can be labeled a racist and nazi for saying that. I was, but then again, I understand, crying "racism" is the weapon of choice for many that hate America.