No, I don't and cannot assess that risk. You could spook them first so that they retract. My guess would be that their feeding tentacles are a bit more selective than a mucus net.Do you have any feather duster/fan type worms? Im curious if this will wipe them out too, I have some pretty cool ones.
I can say that the following corals don't mind CaCO3 at all. Even direct shots via syringe.
Acropora
Zoanthids
Scoly and trachy
Tube anemone actually LOVES this treatment for some reason.