It is supposed to be better if you can take out a whole piece of caulerpa rather than cutting it, as the stuff it bleeds is supposed to be toxic. I find whole strings of it to pull out rather than cutting. I then feed them to the tang which hasn't read about them being toxic. I suppose that is just as bad as cutting it with a razor as the tang snips it over and over into tiny pieces...
When the caulerpa turns white/clear and releases the inside liquid into the tank that is called "Going sexual" in the aquarium hobby. It is supposed to allow it to reproduce, but in an aquarium all those cells die instead of being spread out all over the ocean. Then they rot and foul the tank, plus it is suspected they are toxic. Thus you are right. Bad indeed!
I am guilty of rarely removing the stuff, not giving it regular light and it doesn't go out on me. It makes me wonder if there is a trigger involving alkalinity since I focus on maintaining that with daily dosing because I also want to keep my xenia happy and have mostly soft corals that don't need super high calcium. Calcium gets dosed, but I don't push it high. I try and keep the alk around 9. I also dose iodine. Could help, I don't know.
Kate