Yes it is off putting I agree, and I don't like it or approve of it at all! I am the complete opposite personally and try to adopt Niwas strategy. But if you're a pro player or want to be a pro player and you're losing because of his choing, then that's something you'll have to adapt to as long as it is allowed. I doubt Mizutani lost because Harimoto was choing (I don't know, I missed the game unfortunately), but you have to respect the level that he's at, it's astonishing.
You can dislike his behaviour without disliking him and respect his skill. And again, he's still a kid.. kids are kids, does this justify it? Of course not, but if you're an adult and you know this it's understandable. No need to throw out abuse or "jokes" which some people have done. I don't mean you, by the way.