I don't usually criticize Oda as hard as some people here do but unless there's something we don't know, leaving Sasaki alive is dumb as hell. Denjiro was so angry about what happened with Oden that his appearance twisted to the point of looking like a completely different person. Yet he just simply binds a valuable subordinate of his enemies instead of dispatching them. This doesn't seem in-character to me unless he's going to interrogate Sasaki. We'll have to wait and see. Problem is, Sasaki appears to be the uber-loyal subordinate archetype so good luck with that.
If nothing happens and Sasaki escapes, then it was a completely pointless scene that Oda didn't have to show us. Hopefully he has something planned.