Actually, it depends on the intentions. If it was implied that Indians are inferior because they eat with their hands, then it is racist. Now they don't have to like it. Heck, they can even be disgusted by the practice. That'll be stating an opinion. However, if they look down on Indians for that reason, then it would be racist.
I also make the difference between racism and racist bullying. I am not sure if the lot would behave/say the same thing if it is the another Indian. If they do, then I would say it is racist full stop. If not, then it is using racist remarks, not for the sake of being racist, but for the purpose of bullying. I see it like insulting someone's mother. There is a high chance that the person doesn't know and really intend to insult the mother, anymore than trying to make the victim feel offended/bad and such.
Racist or not, the gang do not appear as being genuinely nice people. Perhaps they would not be this way under another circumstance.. but it does mean that comes down to it, they would act as they have.