A conservative would have threatened the Nazi status quo, and would thus be an extremist according to your definition.
In pre-war Germany, the conservative was the status quo and the Nazi the extremist
In the space of a few years in Germany the status quo and the 'extremist' swapped places per your definition, then immediately flipped back post war.
Threatening the status quo cannot be a logical gauge of ideological extremism can it?
It's pretty much the only gauge. What's difficult is figuring out who represents the status quo, because as you appropriately pointed out, the ideology of the rulers is often not aligned with the ideology of the ruled. In which case the rulers may label the ideology of the ruled, "extremist", when in fact it's the ideology of the ruled that is the "norm" within the social collective. And it's the ideology of the rulers that is the toxic aberration. And I would go so far as to use the current dynamic between the people and the ruling elite in the U.S., Great Britain, and several other first world nations around the globe as an example of this. Although it has not yet reached the point of maximum dissolution, yet.
It's the same thing. The 'collective' is simply an aggregate of individual subjective interpretations
And that's what establishes what is the "norm", what is the "status quo", and what is the extremist aberration. This doesn't happen individually. It's not an individualized (subjective) phenomena.
Joining a million subjective perspectives together doesn't magically make them not subjective.
There's no magic, just logic. Within a million subjective opinions we can establish an objective norm. And it is relative to this objective norm that we determine the status quo, as well as the extremist aberration. And the extremist aberration always presents a threat to the social norm (unless it
is the social norm), and thereby to the status quo.