Rebbe,
Everyone in the daf shiur was stumped by the same question. How can R. Yossi HaGellili hold that chametz is mutar b'hanaa? What about baal yareh u'baal yimotze? How could someone have hanaa and not be oveir on the latter which is a D'Oraysa?
B'kavod,
Sam Kosofsky
Rebbi Yosi ha'Glili is not saying that Chametz should be benefitted from on Pesach, but rather that there is no special prohibition. A person would not have to do Teshuvah on the fact that he benefitted from Chametz.
Additionally, if there would be a case where someone would not transgress Bal Yimotzei, as per the case of two partners who both together own a Kzayis of Chametz (see Minchas Chinuch Mitzva 11:3), they would each be able to benefit from their share of the Chametz.
All the best to everyone in the shiur,
Yaakov Montrose