Sam2, why’d you say that? We find often in Gemara statements about Talmidei Yeishu Hanotzri. I would say the other way around — calling him Oyso Ha’ish started later, when we had to start avoiding the censors.
Oomis, the Halacha is that we are not supposed to mention the name of an Avoda Zara, Lo Yishoma Al Picha. That is what we are doing by not mentioning his name. If you may not eat something it can be because it is Kodshim or Tamei. Same here.