Your argument from Kirin stems from the fact that Zetsu mentions it being impossible to evade since it moves at the speed of lighting and as such, it's illogical for Naruto characters to be able to move Multiple times faster than that.
1) Zetsu, as an intel gatherer for the Akatsuki, has a wealth of knowledge on the capabilities of numerous shinobi. As a result, it he says something is impossible to evade, it should more or less be a fact that applies to even the top tiers, however...
2) Sasuke makes a direct comparison on the difficulty of evasion between Kirin and Amaterasu. Even if we want to say that he wasn't talking about speed, the fact of the matter is that they are comparatively, just as difficult to evade as each other, yet, the Raikage, an arc later, evades it. How did that slip from Zetsu? Of note, the Raikage didn't use some clever means but only pure speed.
Now, let's say that Amaterasu is difficult to evade because you would need to outspeed the opponent's perception and not necessarily the jutsu itself. Even, then, it would still indicate that Ay is > than Kirin. It's important to realize that Sasuke's current perception with his Mangekyo should be around the level of a dying and nearly blind Itachi, the same Itachi who was able to perceive and react to Natural lighting. If Ay is > than that perception, then Logically he should be faster than Kirin.
If the above is true and Zetsu's statement is taken at face value, it means that:
1. Zetsu apparently had a hole in his research if he didn't know there was someone capable of dodging Kirin.
2. Zetsu's statement of "Which is why it cannot be evaded" doesn't seem to imply he's saying something along the lines of "No shinobi can evade it". It seems more so like he is reiterating Sasuke's point with a reason (it being lighting speed) than making a blanket statement.
3. A statement made in the middle of Shippuden doesn't hold through for the series later down the line. There are always going to be things hyped up with "Impossible to block" or "impossible to dodge" yet somehow, those are soon proven untrue. I don't think Zetsu's statement should be taken to mean no shinobi Dead or alive can dodge natural lighting ever. It doesn't even seem like he's implying such a thing when you read the full chapter.
In conclusion, the thing about Kirin being impossible to dodge as Stated by Zetsu is disproven when Ay later dodges a comparatively as difficult to dodge technique. Ignoring speed, Ay was still able to outspeed the perception of Sasuke who logically should have perception > or = to a near blind and dead Itachi.