The article you linked doesn't say anything to backup your claim. United was employee owned for a total of only 6 years. Employee ownership was institued over some employee objections and wasn't fully supported by management. The labor relation issues that caused the pilot strike and slowdown duering that period predated the employee ownership initiative.

Nobody is saying that employee ownership is a magic bullet that fixes organization disfunction but data from that first year does show that it can have a positive impact of performance and customer satisfaction.