Take it with a grain of salt. He's not a professional historian (his master's degree was in computer science) and he has a nationalistic agenda. The mission statement of his organization is to "document the contributions by India to world civilization".

In fairness, he actively distances himself from the pseudohistorical work of far right Hindu nationalists (claims like India invented nuclear warheads in 2000 BC or the Hindus discovered the Americas). He has said that "the quality of the Hindutva scholars leaves a lot to be desired". However, his books are still politically motivated pop history. You should avoid citing his works for the same reason why historians avoid citing David Barton's Jefferson Lies, Howard Zinn's A People's History of the United States, or Gavin Menzies's 1421: The Year China Discovered America.