Public service unions (teachers, police, corrections) are of course highly political and often get involved in things way beyond work conditions and pay.
In the current political environment it’s not a stretch to imagine a union attempting to change Wiki policy to achieve political goals. Wikipedia is a public good and I would highly oppose this.
I’m more pro-union than most, I support having a union rep on the board as in German companies, but I think this should come with both designated powers and limits. The union gets a vote on the direction of the company, but they don’t get to dictate it, which would effectively be a seizure of the company. When it comes to work conditions and pay, they get a much stronger vote, strong enough to force fair compromises. That’s the union deal.
Co-ops are a better model for workers who want to join a company where they have full democratic control.