I've never seen UWC claim that it only impacts micro algae. Most people use it to treat macro algae such as hair and bubble algaes. Any algicide can cause the loss of anything that feeds on that algae if used long enough.
It seems obvious that Vibrant is not an appropriate product for your system and I'm not trying to convince you to use it. Any time we add something to our tank we expose ourselves to a risk. If an issue is minor then the risk isn't worth it. Even if you had a major algae issue, this still wouldn't be good for you.
Reefs are a very complex biological system and each system is unique. With situations like yours, I think of Chemiclean. The vast majority of people can use Chemiclean with no issues. Every once in awhile someone will use chemiclean per the directions and completely wipe out their tank, coral and fish. Why? No one knows for sure but the thought is that these systems must have something in them that triggers a toxin release when exposed to chemiclean. Another good example is with coral foods. I know some people that love Reef Roids. I know other people that can't put it in their tanks without having a massive cyano outbreak. Why? Who knows. The biology of the tanks is just different enough to make it cause problems.
Your coco worm is a good example of this. Does Vibrant hurt them? No. Could it be interacting with something in your tank that could hurt them? Absolutely. And odds are the Coco worm is acting as an early warning system that it releasing something into the water that is also negatively impacting other tank inhabitants. If I had seen an unexpected reaction such as this I don't think I would have made another attempt with the product.
Why am I confident that Vibrant doen't harm them directly? This is a picture taken this past weekend in my tank. I added my every other week dose of Vibrant that morning and took this picture just before noon. But again, just because it doesn't harm them directly doesn't mean I'm saying that it isn't the trigger causing harm in your system