Yoma 38-NEW Sheim Reshaim Yirkav

First of all, why is Ben Kamtzar called a rasha for not revealing his special method of writing? Furthermore, according to the Gemara, it means that his name is supposed to fall into disuse. Do we know that no one else was called Ben Kamtzar? Also, from this Gemara it would seem to be very difficult to determine who is a rasha. For the record, Maharsha in Sanhedrin (Chelek) says that Korach was korcha (bald) baolam, becuse no one after him was named Korach. (There's a Medrash Rabbah that states that no one ever calls their children Sancheirev, Pharaoh, etc, and that implies that we only don't use names of wicked goyim.) Chasam Sofer asks the other way, how could Shevet Levi call their prize son Korach, if one of the alufim of Esav was called Korach. From Tosfos here s.v. delo it seems that if there's another Korach who was not a rasha, it's ok. I don't remember if Chasam Sofer says this answer or someone told me this.