I can't read the article because paywall, but I assume this ruling is based on the fact that political parties are "technically" private entities and therefore primaries are "technically" legally-meaningless private contests that said parties can run however they want.
Which is all bullshit, of course -- if political parties were truly private then they wouldn't get any support from the state whatsoever to run their fake elections, for starters -- but just goes to show how their corruption and power lets them (as de-facto government entities) get away without accountability or oversight.
Judge James Robert Redford of the Court of Claims in Michigan said that the disqualification of a candidate through the 14th Amendment “is a nonjusticiable, political” issue and that it was up to Congress, and not the courts, to settle the matter.
Basically he said insurrection can't be defined by the court system..
Sounds a lot like passing the buck. Or taking a page out of the SCOTUS playbook.