No they aren't. Sri Lankans are a completely different nationality made up of different ethnic groups, they speak a different language, practice a different religion (in fact it's Buddhism and the exact same form of Buddhism practiced in Thailand) and they have their own culture.
Maybe don't judge an entire group of people based off of one person. Can't you see that the family was trying to calm the man down? Obviously he has some issues but it has nothing to do with his ethnicity. This is like generalising all Australians for some of the things they have done in Southeast Asia.