Here is his body after the attack, he never flew.
he was on the floor before that and just lifted his neck to bite luffy.
On that panel he was on the floor, luffo knocked him over, he didn't rise very high after that:
OBS: You can see that the KID is the height of its side, not so far from the ground.
Here he shows that he appears to have leaned on the ground or curled up on a mountain, which confirms that he was very close to the ground.
From Zoro's point of view, KAIDO is not that far from the ground:
And the other panels just confirm that he twisted his neck (S) in an upward curve, he was not falling. !!!