The word “tradition” is generally negative in the New Testament. Jesus was never other than a shocking figure whose interpretations were mystifying or eccentric to the rabbinic tradition which saw itself as the authorized interpreters. The verse you cite, 2 Thess 2:15, does not help your point.
So then, brothers and sisters, stand firm and hold fast to the teachings we passed on to you, whether by word of mouth or by letter. (NIV)
I also invite you to do that. Stop reading agents of a later tradition. It is not given any authority. It is a set of speculations by later people who lacked basic resources coming available now—like, for example, what words mean.
You could start with Kyle Harper’s paper on porneia, which notes its meaning isn’t really known. Gregory of Nyssa, the 4th century “Church Father,” quotes a meaning different than any used today.