The person you are replying to seems not to be disputing this history, but moving onto the "..but if it did happen it was a good thing" stage of the argument.
I am only highlighting that the oft-repeated claim that America was conceived as a nation of non-discriminatory immigration is a lie. It only moved in that direction with the Immigration and Nationality Act of 1965.
But I sense you're having fun being so vaguely edgy and contrarian so I don't want to further encourage it.