Is the Torah of Har Sinai to be ignored in favor of the second Torah’s oral arguments and disputes of the Talmidim, Rabbanim and Scribes?

http://whoarewisemen.homestead.com/Erubin21b.html

http://whoarewisemen.homestead.com/TalmudorTorah.html

Can anyone explain what is meant by the dark boxed section of this section of Talmud?