While the edos were on the ground, severely crippled by the paper bombs, Hiruzen could have done more damage or used a sealing jutsu to finish them off. Jiraiya can last against Orochimaru without sage mode. He might not win, but he certainly won't go down easily.
Edit: I think it's also important to note that those edos weren't as powerful as the ones used against Juubito.
Orochimaru wouldn't have been so arrogant. Orochimaru alone is stronger than Jiraiya, which was stated, and proved. Hokages could keep Hiruzen busy until Orochimaru tongue chokes.