I think he is a little childish or rather immature mentality and that should be bcos of his upbringing, probably over protected or his parents didn't have the right method of bringing him up. It's not entirely his fault. Look at season 1 when Gai the rapper couldn't cope with the dance moves 1 of the member suggested to simplify it for him he flatly refused it. He was actually in tears bcos of the frustration in him but he still rejected it and says that he will overcame it with lots of practice. He didn't ran away. At the actual performance Gai was well above expectation. Gai put in lots of effort to be what he is today where as Siang Zhuo had an easy childhood with a golden spoon.