Of course, that gemara was written hundreds of years after the books by those who never met him. The gemara was also written in a non-christian country. The amoraim had no interest in some apikores from a time when false messiahs were a dime a dozen. It could have been yeshu, it could have been one of the many people whose (mostly fictional) biographies went into the Christian canon. OTOH it could have been just another apikorus.
goodbye: isn’t it “chisurei” hashas, not chisronos?