I don't pretend to know anything, hence why speak of "personally" and similar words. I'm doubting the assumptions of others here.
I don't really despise Zorofans as a whole, although (out of this debate) I do indeed despise particular individuals among his fandom; just like Oda would, and here I'm completely sure of it. But this has nothing to do with this thread.
What I'm questioning is your understanding of Oda's work, not by taking the position of assuring I know it better but by doubting his is the same as yours.
"Who was fucking around" equals he was about to kill, which he was?
Just like the Straw Hats had a prolonged fight with a significantly stronger foe, and? It's like you guys don't know how Oda's teamfights work, especially one so badly managed as this one (which feels like a staring contest for its most part).
Aokiji is one top tier and Ace did better than Zoro, so balance.
Armament haki is applied over your direct body. Swords aren't part of your body. Obvious difference there in terms of blocking.
The full summary makes it even more nuanced because Zoro ends up heavily injured.
And Kuzan was about to kill Robin, he didn't inted to spare them from the start.