It seems to me the author, much like in the title itself, starts with a very large thing (rock) and ends with a very specific one (Nordic metal) identifying a shift.

But it seems class-war style rock was still very much a thing over the last 30 years, it just moved to hip-hop adjacent (e.g. rage against the machine), and the author decided to just focus on the part of the huge rock galaxy that did switch to far right.