Prove he doesn't have Indian citizenship. I recall seeing it mentioned, but haven't seen anything recent. I don't recall any interview where he was asked if he is still an Indian citizen or if he renounced it and when. Until otherwise, since he was born of two Indian citizen parents, raised in an Indian family, retained their culture and religion, travels to/from India, married an Indian, raising his kids as Indian, I'll rightly presume that he is still an Indian citizenship.
Dual citizenship is legal in the US, questionable if it is true as president for dual-loyalty, but we've see others recently with two or more citizenships. I don't like it an as a voter I will NEVER vote for a candidate in any role that holds foreign citizenship.