Perhaps, but if we look at the data above, the rejection of MSM sources extend over decades.

I'm not American so the 'Republican' label here in Europe would overlap more with populists and the anti-establishment movement.

The UN Agenda 21 was signed by 179 nations in Rio de Janeiro back in 1992. If we want to analyze the operative system of the "establishment" we can simply review the policies (code) that Agenda 21 involves. It is a very comprehensive plan for the 21st century involving a false "sustainability" program, which was inspired by Club of Rome as they were searching for reasons to implement global regulations. A climate scare fitted the bill.

Since it was easier for the establishment to achieve the Agenda 21 goals on a social-democrat platform, this is likely why we are seeing an overlap between republicans/conservatives and anti-establishment movements for the past 30+ years.