Zoro was disgusted.
This guy called himself a swordsman?
All his cheap tricks, aiming for a man's injury, letting somebody else interfere in a swordsman's fight?
He was no swordsman. He was a cheap parlor trick carrying around a sword.
How dare he call himself a swordsman, let alone think that he could ever beat Zoro in a real fight? Honestly, if it weren't for his circus side-show, Zoro knew the fight would never have gone on for as long as it had.
That's what he was really disgusted with, though, not the wanna-be in front of him. But that it was taking so long to finish it, and that he was taking so much damage.
He regretted asking his captain to let him handle it. This was the most embarrassing fight he'd ever been in, and if anybody from his old dojo saw this, he would never live it down.
He sighed and stood up to deliver the final blow, knowing that he was going to go ahead and pass out after this, from blood loss.
The next guy on a unicycle he saw, he was avoiding, no matter how much of a threat they thought they posed.