I didn't read the paper, but this sounds very familiar and similar to the change in the NRA.
Pre 1970s the NRA was very much a hobby gun club meant mostly to keep american boys/men using guns for war readiness, along with promoting hunting/outdoor recreation. Then, in the 1970s, the NRA changed tune. After a big leadership shakeup the organization became very proactive in promoting anti-government, 2nd amendment, and "patriot" ideals. This likely stems from the Nixon impeachment, wherein republicans felt "wronged" and actively started seeking out revenge.
The federalist society was also born out of this same period and sentiment. The sentiment is that nixon's impeachment was a hit job. That's when we saw the advent of conservative media and the idea that "emotions are more important than fact" started to get some traction.
There's a great This American Life episode on the NRA's transformation from a hobby group to a lobbying group. I think this is it, https://radiolab.org/podcast/radiolab-presents-more-perfect-... . Great episode, highly recommend. It really puts the whole 2a movement into perspective.