I agree in removing from the tank to cut them for our safety, specially!
Sometimes it's just impossible though.
I've never had any fish dead because of that.
I don't think I've never heard about fishes and/or corals harmed because of Palytoxin, mucus or other toxins in the water either.
I've heard about chemical warfare related to sweeping tentacles (stinging cells). Also overgrowth could happen with zoanthids and some corals, of course.
Am I wrong?