Yes. Ethnic discrimination is absolutely unacceptable in any American workplace, full stop. There is no room for cultural relativism here. To imply otherwise (e.g. “it would be inappropriate for a non-Indian manager to tell off their subordinate for being caste-ist”) is itself extremely racist.
Again, how is that determined? Do you assume that a caste angle might be at play every time the manager is upper caste and the employee's of lower caste? Do you wait for the manager to be stupid enough to outright utter a casteist slur at the workplace?
Maybe I have a different view on that, we German's are quite sensitive when it comes to anti-semitism. And as woth caste, if religion is never openly discussed, I have no idea how to spot a jewish co-worker. If that jewish co-worker would complain about about being discriminated, it's more than reasonable to follow up. Same goes for caste. It is up to the employer to create an environment where employees can raise those kinds of concerns openly, most fail. Honestly trying so actually goes along way.
You are just saying that it is the job of the super-manager to find out why without answering how the job is supposed to be carried out. The manager says he is acting against the employee because of their lack of performance or insubordination. The employee says the manager is discriminating against them based on caste. You're the super-manager, what do you do?
Not sure what a "super-manager" is supposed to be. Everyone reports to someone, even the CEO reports to the board. And the board reports to the shareholders. If a company cannot figure out cases of discrimination it is already screwed.
In real life, so, the disriminated party either gets a transfer or a generous severance package. Even if the discriminating manager gets fired. Nobody likes people that make waves.