what if sarutobi's cancellation of the 4th's summoning effect was permanent and oro can't call the 4th anymore?
what if sasori is capable of doing the same thing that sarutobi did if oro can call him up again and attempts to?

Sure oro knows sasori's fighting style, but sasori knows oro's fighting style too.

The only valid argument that supports oro winning is that oro consciously arranged to attack sasori at the bridge, and he wouldn't do that if he didnt think he stood a chance at winning.