There is nothing wrong in someone wanting to protect their existing culture. There is beauty in preserving an inherent culture, by opening it to everyone it would go away.
This guy is using caste card to embarrass them. We all know what happens when we let migrants in to your home too much. It's the same everywhere, first they go and take the local set up for granted. Don't learn their language, don't try to be part of it. Won't even care when the local culture disappears, the moment a local objects to it, they go to Twitter and start this randi rona.
No one does caste discrimination anymore. But caste or otherwise, food language and behavior defines boundaries, irrespective of caste those should be respected