Because he didn't.
He posted a pic of Akainu, but got the attack wrong lol. Also, it was disingenuous too, since the attack, the Ryusei Kazan, was an area attack that did a lot of damage and was not even directed at WB.
Kuzan's was, but ice is weak to fire, no haki was involved, so naturally got neutralized.
And the funny thing is my point was not even that: I said that Kizaru have still a lot to show, since their animal move is usually entry level (I even said that) and is usually used soon, but in Luffy vs Kizaru we did not even get to see it.
In other words, we are discussing about the bare surface of Kizaru's repertoire for now.