Yes, the noun lacks any conceptual clarity and has been used to describe anyone from Internet trolls, to provocateurs like Milo Yainnopoulos, to right-wing nationalist like Richard Spencer. Then again, I think that is part of the point Vegter is trying to make - that it is being used as a cheap political label. 

An aside, I think it is inaccurate and problematic to think of Trump supporters primarily in the context of alt-right and white nationalists. Unfortunately "nationalism" has also been tarnished a lot of late with political smear. 

I would venture a big part of the Trump base is just what you would call "patriotic-lite" / "America first"  (dare I say folksy libertarianism) in the sense of not dismissing the people, old industry, cultural heritage, American values, traditional institutions and caring first about jobs, safety and rule of law - as opposed to some hyper nationalism in the guise of say the NP or Nazi Germany. 

The left used to win and attract this voter too...