No, we don't know if Hidan won't hit Itachi.
Since when did blocking an attack from someone mean you can keep up with them? If Gai ran up and threw a punch, 99.99% of shinobi will block it. When he throws several and enters into a super taijutsu combo is when he beats the shit out of you and that's when one realizes they can't keep up. Any boxer can block a Mike Tyson punch but it doesn't mean they can keep up with him because right after he goes apeshit and knocks you out before you know it.
I guess Jugo blocking Ay means they can keep up with him.
Or Suigetsu blocking Bee means he can keep up with him.
Or Muu blocking Ay means he can keep up with him.
Or Haku blocking Kakashi means he can keep up with him.
Or Gaara blocking Lee means he can keep up with him.
I can go on and on....
Anyone can block an attack. Your scan of Itachi blocking Kabuto doesn't prove Itachi can keep up with him in CQC. All it proves is Itachi can block a single strike from Kabuto because the above people did the exact same thing against people far faster than them and
WE KNOW the above will roast the shit out of the people who blocked them in CQC neg difficulty.
Right, a few paper bombs will hurt the guy who tanks forest busting
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with no scratches and already tanked a paper bomb
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with
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so itachi better have 100+ paper bombs and stick them all to Hidan body to blow him up at once or this becomes a fight of attrition which Hidan undoubtedly wins.