My man Togashi literally just said in the tweet that he wanted to puke but somehow "he's back for good"
Also imagine believing the colour spread thing that you said like he would notice such an obvious thing only 18 years after his first hiatus.
This post had nothing to do with his physical condition.
It's just that he was annoyed about his difficulty drawing a certain character angle (aka "Man, it's so annoying I want to puke").
On top of that he's had several posts where he said that he is feeling healthier and almost completed 20 new chapters (sth we haven't gotten in ages) that are going to be released starting early October.
Sure, you can never tell what happens, but for Togashi that run qualifies as "being back for good".