Lol, Im Polish, Russian and Irish. Depending on how stringent someones criteria is, I may not even qualify as being genetically "white" and my people were also the "product of bad lazy people...", etc.
I'm Italian, Swedish, and... I dunno, French and English? My name is Italian, so that would have put me in the "dirty people" group through the '60s or so.
You can bury your head in the sand and virtue signal til the cows come home but the truth is people are different. The behavior of individuals is impossible to predict, but not so much with groups of people. The country was founded by white christian people who shared a common set of values.
Kinda... They were mostly white, but religiously and socially quite different. Religious intolerance was pretty common in the American colonies. Catholics and Jews were the "dirty people" before the Irish and the Italians. Quakers and Shakers (that ... sounds weird) and Catholics and Methodists and Lutherans didn't exactly see eye-to-eye on things.
America's True History of Religious Tolerance | History | Smithsonian
It's not like it all went away with a couple hundred years of "assimilation". Pretty much every other part of the country thinks New Englanders have some crazy puritanical views on the world. (and they're right. I was born and grew up here and it's quite clearly true)
They had a code they chose to live by. Things they valued and things they abhorred. The system of gov they instilled depended on people sharing those values. Individuals from wherever may or may not choose to live by that same code. Groups of people tend to live by the code they brought with them.
Brown people coming here and marrying with whites may or may not be an issue. Brown people coming here and publicly stating they are going to do their best to one way or another breed another group out of existence will eventually be a problem.
How do you imagine "breeding another group out of existence" without "interbreeding"? Do you imagine they're going to keep other people from having children?
Its one thing if someone says they love your daughter and want to marry her and start a family. Its another when they laugh in your face and tell you your grand babies are going to be brown. I dont think anyone of any color would appreciate that (aside from virtue signaling white "males")
Wat? You're either suggesting rape, or deliberate intermarriage. The first is clearly bad, (and I don't think any group is suggesting it) or it's what you just said was OK.