Communist SJW BS IMO. Correlation does not necessarily equal Causation.
Airplanes without premium seating are typically smaller RJ's or turboprops. Shorter flights, shorter lines, shorter boarding time, less opportunity and time to get drunk.
And the only big planes with no premium seats at all are ULCC... so ULCC pax are better behaved??? Tell that to a spirit pilot.
Also chicken or egg? Are premium pax better behaved because they have money and comfort? Or perhaps they have money and comfort BECAUSE they are better behaved.
I might buy their premise that premium pax exhibit a different flavor of misbehavior, when they do misbehave.