I never implied that Newars have not beaten up people from madhesh origin. I am sure some Newar/Bahun/chettris have been beaten up in madhesh too. But that is not the point. The main point I want to make is that some Chettris still to this day think they are the warrior class and that they are born warriors which makes me puke at their ignorance.
Some of them want to show off their warrior skills by beating up or bullying the weak and the poor.

Like I said, even a tame dog will bark and bite you if you taunt it too much. Warriors are made by circumstance and perhaps training, and nothing else.