Ill or not, it doesn't excuse putting out chapters with art worse than what I could draw by downing a whole bottle of laxatives and gripping a pen with my anal sphincter.
If he was really truly ill to the point where he couldn't even draw properly, he would have gone on hiatus earlier.
He didn't even have his assistants do semi-decent backgrounds (in the shitty chapters there were often none at all) or touch up the characters with a bit of toning or inking. They were just pure scribbles. Utter shit.