Just a matter of time before Oro ices Danzo. Rather than breaking down conditions or abilities, I thought about the following things.
1. Before the invasion, Sarutobi said there was no one in the Leaf Village at the present who could go toe to toe with Orochimaru and hope to finish him off. Danzo was residing in the Leaf at the time, yes?
2. Unless there is a flashback someday showing he actually helped out during the Invasion, can we assume Danzo was either battling a few harmless Sand/Sound Genin far away from serious danger or hiding in the closet of Iruka's classroom at the Academy? Of course I understand he hadn't been created yet, but again he was somewhere in the village.