By "emotional attachment," I think he was referring to President Trump's mother Mary Anne MacLeod Trump having been born in Scotland in 1912.
Farage is probably thinking that the era of Ellis Island and the European migration to the United States is generationally over with the eventual passing of the immediate families of Ellis Island immigrants like Trump and his affection for his mother's homeland.
Future generations of Presidents won't have parents who embraced the "melting pot" of the United States the way that those immigrants did and then passed those family values down to their children.
-PJ
“I think he was referring to President Trump’s mother Mary Anne MacLeod Trump having been born in Scotland in 1912.”
No. He was referring to the traditional bond of brotherhood between the two nations based on shared culture and ethnicity.
Your take is proof he may be right.