I read this with great interest but also had many questions which arose and as I also received the same article in an email, I inquired about them from the sender.
The fact that Buddhism disappeared from India over a period of about 800 years is not in doubt. Starting right from the great days of Buddhism after Emperor Ashoka gave the most almighty push, a combination of incorporation within Hinduism, emergence of Jainism, the invasions of the Muslims, the sectarian splits between various Buddhists sects, etc. all meant that we do not see Buddhism in India as seen in other countries. But this theory that Brahmins and/or Hinduism eradicated Buddhism does not quite hold.
The theory by Naresh Kumar is quite an interesting story, but unfortunately not really catered for by valid references. I wouldn’t expect references in an opinion piece, after all it is not an academic journal article, but I would expect at least a nod given to the contradictory evidence as well.
For example, it was during the Buddhist times, around the 2nd century BCE, that the original Ashoka stupa at Sanchi was vandalized and then a bigger stupa built over it. I wonder who it was who restored the original Ashok Stupa? While, for example, it is well known that Pushyamitra Sunga was responsible for the destruction and had a hatred for Buddhists, this does not explain why his son would rebuild it. (Hint, check out Romila Thapar's work on this curious incident).
How about the White Huns and their impacts on Indian Buddhism? Their invasions had a huge effect on ancient Buddhism. As for welcoming Muslims as saviors, I am curious how he justifies the arrival of Mohammad Khilji and say for example the destruction of Nalanda, the premier Buddhist University?
And how about Harshvardhan, who was perhaps a bigger secular leader than Akbar himself with his tolerance and willingness to support multiple religions? Curiously, the author does not talk about say the Kalchakra Tantra (which can be said to have emerged as a reaction to the Muslim invasion) or even compare it to why Buddhism survived in Sri Lanka and not in India. Mind you, the argument can be extended to South East Asia as well.
Also, many Buddhist kingdoms were succeeded, especially in the west of the country, around the Gujarat and Malwa region, by Jain kingdoms.
How does that compute with the general overall hypothesis of the author? The author also seems to have ignored the rather large oral and written corpus over the concept of Buddha as a reincarnation of Vishnu. He talks about the Vishnu purana and says that the Buddha is the great seducer. Now this does not make sense, because according to the Vishnu Purana, Buddha is one of the 24 or 29 or 10 (depends upon which shloka you read) avatars. Now all I can presume is that because the previous avatar was Krishna, who was called as the great seducer, the author has gotten a bit confused between the avatars. I cannot understand how the author could say that the Buddha was said to be bad, when he is supposed to be an avatar of Vishnu.
I realize that the Buddhists and Dalits are trying to build up their own identity, but relying on wrongful views or misinterpretation of history will lead to two things. One is people chuckling at you and second is a weak identity. You don’t want either of these, so I would suggest that either the arguments about the disappearance of Buddhism in India be more factual or better researched, preferably both. And before you complain, I claim the Buddha as my own God as well, so don’t you tell me that it has nothing to do with me!