The claim is predicated on the mutual understanding that being a white nationalist is bad. If you lack that mutual understanding, there are bigger problems at hand!
Reactionary != White Nationalist
* a reactionary government * reactionary politics"
That's about half of the people in most countries, so your argument just ends up as a sort of statement of your political beliefs.
There are more pejorative uses of the term; I guess we just end up in a semantic debate.
There are certainly places in the world where there are significant local reactionary ideologies that are not White Nationalist, but the US is not among them.