With my gemara learning training to back me up i suggest that the amoraim did not argue as to the evil of not being tocho kboro, but rather they argued as too whetger such a person should be allowed in the bais medrash.
On the day they did open the doors, and another several hundred came in, some amazing things were accomplished in one day! There was not a single sofek left. Everything was clarified on that day.
How can allowing “evil” people in merit these accomplishments?
Even Rabbon Gamliel didn’t consider it evil. He just didn’t allow them into the Beis Midrash together with which holy Tanoim who were able to revive the dead. Let them learn elsewhere until they reach the level of “tocho kebaro”, and then come join.