^No actually Hidan did react to Shikamaru, being able to block = reacting. Dodging isn't the only method of reacting. Only thing was that he was surprised by the fact that Shikamaru decided to fight up close.
Also this panel
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shows both attacking each other, fairly even speedwise with neither gaining the upper hand over the
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.
And dont bring up the Kakashi was just defending argument originally yes but you can see they started to go at each other around the tree and then the final clash was clear cut. Similar to him clashing head on with
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mind you Asuma and Kakashi have the same speed in the databook although its not the best measure. Despite it being 2v1 he was the one that landed the blow on Asuma while simultaneously dodging Shikamarus shadow
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. From these feats it is clear he could have tagged Shikamaru if he wanted but CIS and PIS were involved.