It said, "Any person who would be impure from a corpse...celebrates it a month later". This tells us that any individual is barred from bringing the sacrifice, but the community is not. That was the suggestion of Rabbi Yochanan. However, his student, colleague, and constant opponent Resh Lakish suggested that it could mean the following: an individual has a way out by celebrating Pesach Sheni, but a community has no way out at all. The Talmud goes through a string of proofs and confirms our rule.
Art: The Death of Marat by Jacques-Louis David