I worked at an aquarium store (probably one of the ones mentioned in the story) for a long time, and was a pretty experienced and dedicated reefkeeper at my peak, and I never knew this.

This situation must be incredibly unlikely though because I've dealt with thousands of Zooanthids and hundreds of customers over the years I never had anything like this happen nor heard about it from anybody. However, I certainly wish I had known so I could have warned customers about the risks, because in the aquarium world Zooanthids are considered a great starter coral because they are very hardy and don't require much light.