I don't think it's stress with these guys. For example, my HM Angel was a quiet, still little thing until he gave himself a trim. Now he's WILD and full of personality. Their tails bog them down and once they learn that fin trim = freedom, well....you get the idea.
It's a shame though. I thought I finally had a non-tailbiter but I was wrong. Cloud just started ripping his tail to bits tonight.
I only ever had one half moon (rosetail) that didn't bite. Plato, a beautiful platinum butterfly. He had such graceful control of himself, he would slowly swim across the tank and then display and float wherever he pleased. Sadly, a mystery disease took him from us and we have been so devastated since. I was basing my whole line on him.
Anyway, just make sure to keep the water clean and you should be ok concerning tail rot.