Kids are watching and he became a starter which means they are idolizing him now, time to change and be patient for there are young ones who are looking up to him.
Clarkson is ready to square up, he is really all the time, that's his trademark, LOL>.
Seriously, you are right because he should set a good example, maybe he was annoyed but he wasn't too smart to control his emotion, which is not good for his career and for his team. Look at Jokic, he is good in the regular season but once he is in the playoffs, the tactic of his opponent is to put a very tough defense on him to annoy him and probably make him lose his focus.
Sad to say, but that is true, they are Pro and they should keep that way, I understand that there are always emotions when playing, especially when you are aiming to win for your own pride.
But it won't help you as an individual, just like with your example, it can be used against you
if other players notice that you have that kind of emotions, they will simply use that to
keep annoying you to lose your focus.