Rav Nachman and Rav Sheshet disagree regarding whether impurity is pushed aside or entirely permitted in cases involving the public. The gemara brings three tannaitic sources (including Tosefta Menachot Chapter 3) to raise difficulties against Rav Nachman, but answers them. From the answers, it becomes clear that Rav Nachman held that there were a few exceptions to the rule and there are cases where the impurity is not entirely permitted. Then they bring one source against Rav Sheshet and answer it by saying that it's a tannaitic debate whether or not impurity is pushed aside or entirely permitted. The tannaitic debate relates to the tzitz of the Kohen Gadol and whether it worked while it was on his forehead only or even if it were hanging on a peg. Some of the other sources brought also mentioned the tzitz and discussed when it was needed.