French politicians make statements about Quebec is because of generations of immigration has built historical and cultural ties between the US and Ireland and between Quebec and France

It wasn't French politicians, it was just De Gaulle. And he did this barely two decades after Canadian soldiers died liberating France in WWII. The French-Canadian PM basically forced De Gaulle out of the country in response and the domestic French press tore him apart.

My point being that unless there's some major humanitarian crisis going on, it's not the place of foreign politicians to insert themselves in separatist conflicts in the territory of their allies.