So basically you never become a native regardless how many generations you stay in a country, thus nationalism is valid point of view.

I didn't say that :-)

I was commenting on the use of nativism by a politician whose grandfather was an immigrant.

Though over time some groups formerly seen as undesirables become honoury whites Irish German Catholics etc.

It wasn't that long ago that having a catholic president Kennedy was seen as problematic

Sure, but how is it ironic? That is what I'm trying to figure out.

irony "a state of affairs or an event that seems deliberately contrary to what one expects and is often wryly amusing as a result."