Supposedly it was corrected (I doubt permanently) when a CO with a little sense left showed up. He wore non-white shirts for his talks.
Not really an urban legend. I personally know of this happening. I was just a boy in the early 60's, my father was the congregation servant at that time (he was always more balanced than others) in the congregation. One of the other "servants" brought it up during the Friday meeting with the Circuit Servant and said he felt no man should be allowed on the stage unless wearing a white shirt. The Circuit Servant at that time asked him if he truly believed it was wrong to wear a colored shirt on the stage? The complainer said "Yes". So the Circuit overseer told him, "In that case I NEVER want to see YOU wear a colored shirt on stage!"
That Sunday the C.S. showed up wearing a pink dress shirt. My father was not a liar, and I heard verification of the truth of this story from the C.S. decades later shortly before he died.