What should be done?
Nothing major at first maybe some warnings after the game as he doesn't dima moan during the point so it would be unfair to do anything about fairly won points.
I suspect maybe they should withhold earnings if he gets more than x warnings at first. This shouldn't affect him as most his cash will be sponsorship, just to let him know it's serious.
How do define it as an issue? Well let's limit choing to a reasonable amount. So only maybe 4-5 per set at most. And volume wise he should get a warning if it could affect games on other tables significantly.
Maybe if fines don't work consider like football a system for disallowed entry to the next tournament of note after accumulated sportsmanship issues.
But I dont think it'd fair to remove points or results for sportsmanship issues as he still won the point fair and square.
I wasnt to point out I don't want him to be banned from anything just hopefully it wouldn't get to that point.
Withholding earnings will never happen. Nor will disallowing him to enter...this is the ITTF, not your local club tournament. Harimoto is likely their biggest cash cow right now, and they would have hell to pay with Butterfly, the JTTA, from a legal standpoint etc. until they have an established rule in place, and creating a rule around this isn't easy. At best, I would bank on unsportsmanlike conduct yellow cards, escalating if he continued to do so in a given match.
You also can't limit it per set, what happens if you go deep into deuce or there are multiple excellent points? I think the most feasible would be to do a volume limit but either way he would need to be notified prior to the match about new enforcement rules. And the same would have to go for everyone else.