This nullifies nothing, black Chidori Eisō would cut through it without any problem. Doesn't matter if it's "omni-directional" or not, Sasuke aims at it and cuts it down normally would still work. Don't bring the Jūbidama in here since they weren't senjutsu empowered and thus got nullified.
1. You're underestimating Sasuke's range way too much, this is post Shinju Madara speed we're taking about, do you know how fast he is? He's faster than everyone bar current Naruto and Sasuke, meaning faster the Jūbito, BSM Naruto, etc. He got a good few seconds off before he got out of Sasuke's range, if you do the math it would be pretty far away, totally not "isn't impressive" like you stated. Besides, nothing stops Sasuke from jumping twice if it's a bit out of range, it's out of range for one jump not two.
2. You're assuming Naruto engulfed in Gudōdama would be able to get distance from Sasuke. Gudōdama itself is
not faster than Sasuke, in fact, it is
far from getting close to Sasuke's speed. It is impossible for him to get distance from Sasuke like this. His normal speed let him catch up to Madara, albeit the latter stopped when he got Kakashi's eye and implanted it, still fast nonetheless.
3. Naruto engulfed in this would mean he wouldn't be able to see the outside and locate where Sasuke is. A clueless Naruto gets chopped down by black Chidori.
Naruto does not know where Sasuke is while being inside Gudōdama, and he would have to put the shield down to form the Yōton: Rasenshuriken, creating even more openings for Sasuke, as forming the Rasenshuriken takes time.
The Rasenshuriken can also be easily evaded as seen when Naruto standing still and Gai lying there weren't affected by it. But first he had to connect the throw first to expand, which isn't happening.
He is.